Five years ago, there were 500 old books in the library. Two years ago, the librarian bought 300 books. Last year, the librarian bought 100 more books than she had bought the previous year. This year, the librarian donated 200 of the library's old books. How many books are in the library now?

Last year the librarian bought 300 + 100 =

<<300+100=400>>400 books. Thus, there were 500 + 300 + 400 = <<500+300+400=1200>>1200 books as of last year. Therefore, there are 1200 - 200 = <<1200-200=1000>>1000 books now in the library. #### 1000 Mike decides to do more pull-ups to increase his strength for climbing. He uses the greasing the groove technique where every time he goes into a certain room he does 2 pull-ups. He decides to use his office. He goes in there 5 times a day every day. How many pull-ups does he do a week? He does 5*2=<<5*2=10>>10 pull-ups a day So he does 10*7=<<10*7=70>>70 pull-ups a week #### 70 A group of friends walked into Juju’s Juice Bar ordered a glass of fruit juice each. They spent a total of $94. Some of them ordered mango juice, which sells for $5 a glass, while others asked for pineapple juice, at $6 a glass. If $54 was spent on pineapple juice, how many people were in the group? The amount spent on mango juice is 94 - 54 = <<94-54=40>>40 dollars Dividing the 40 dollars by the cost of a glass of mango juice gives us 40/5 = <<40/5=8>>8 people Since a glass of pineapple juice goes for $6, the number that ordered is 54/6 = <<54/6=9>>9 people Adding both numbers gives a total of 8 + 9 =<<8+9=17>>17 people #### 17 Jerry works five days a week as a waiter and earns a variable amount of tips every night. The past four nights, he earned $20, $60, $15, and $40. How much does he need to earn tonight if he wants to make an average of $50 in tips per night? The total money Jerry needs to make for 5 days to get $50 per night is 5 nights * $50/night = $<<5*50=250>>250. His total earnings for the past four days is $20 + $60 + $15 + $40 = $<<20+60+15+40=135>>135. So, Jerry needs to earn $250 - $135 = $<<250-135=115>>115 in tips tonight. #### 115 At a certain car dealership, 15% of the cars cost less than $15000 and 40% of the cars cost more than $20000. If there are 3000 cars at the dealership, how many of them cost between $15000 and $20000? 15% of 3000 cars is (15/100)*3000 = <<(15/100)*3000=450>>450 cars 40% of 3000 cars is (40/100)*3000 = <<(40/100)*3000=1200>>1200 cars 450+1200 = <<450+1200=1650>>1650 cars which cost either less than $15000 or more than $20000 Out of 3000 cars, there will then be 3000-1650 = <<3000-1650=1350>>1350 cars left which cost between $15000 and $20000 #### 1350 Iris’ family is planning a surprise birthday party for her. The party will include her 3 uncles and 4 aunts who have a son and daughter each as well as her brother and mother. In total, how many people are coming to Iris’ birthday party? Each of her aunts and uncles have a family unit of 1 son + 1 daughter + 1 aunt/uncle = <<1+1+1=3>>3 people. Iris has a total of 3 uncles + 4 aunts = <<3+4=7>>7 aunts or uncles in these family units. So among her aunts, uncles, and cousins, there will be 7 family units * 3 people in each family unit = <<7*3=21>>21 people. Including her mother and brother, there will be a total of 21 people + 1 mother + 1 brother = <<21+1+1=23>>23 people coming to her party. #### 23 Liz sold her car at 80% of what she originally paid. She uses the proceeds of that sale and needs only $4,000 to buy herself a new $30,000 car. How much cheaper is her new car versus what she originally paid for her old one? If Liz needs only $4,000 to buy a new $30,000 car, that means she has $30,000-$4,000=$<<30000-4000=26000>>26,000 from the proceeds of selling her old car If she sold her car at 80% of what she originally paid for and sold it for $26,000 then she originally paid $26,000/80% = $32,500 for her old car If she paid $32,500 for her old car and the new one is $30,000 then, the new one is $32,500-$30,000 = $<<32500-30000=2500>>2,500 cheaper #### 2500 Martin went on an eight-hour business trip. During the first half of the trip, he traveled at a speed of 70 kilometers per hour and during the second half at a speed of 85 kilometers per hour. How many kilometers did he travel during the journey? Half of the trip lasts for 8 * 0.5 = <<8*0.5=4>>4 hours. During the first half, Martin did 4 * 70 = <<4*70=280>>280 kilometers. And during the second half 4 * 85 = <<4*85=340>>340 kilometers. In total Martin traveled 280 + 340 = <<280+340=620>>620 kilometers during his business trip. #### 620 Joey needs to take a new prescription. The first day he needs to take one pill. Each day he must take two more pills than the previous day. How many pills will he take in a week? For the second day he takes 1 + 2 = <<1+2=3>>3 pills. For the third day he takes 3 + 2 = <<3+2=5>>5 pills. For the fourth day he takes 5 + 2 = <<5+2=7>>7 pills. For the fifth day he takes 7 + 2 = <<7+2=9>>9 pills. For the sixth day he takes 9 + 2 = <<9+2=11>>11 pills. For the seventh day he takes 11 + 2 = <<11+2=13>>13 pills. For the entire week he takes a total of 1 + 3 + 5 + 7 + 9 + 11 + 13 = <<1+3+5+7+9+11+13=49>>49 pills. #### 49 Mandy has three $20 bills while Manny has two $50 bills. If both of them decide to exchange their bills for $10 bills, how many more $10 bills than Mandy will Manny have? Mandy has a total of $20 x 3 = $<<20*3=60>>60. So, she will have $60/$10 = <<60/10=6>>6 $10 bills. Manny has a total of $50 x 2 = $<<50*2=100>>100. So, he will have $100/$10 = <<100/10=10>>10 $10 bills. Hence, Manny has 10 - 6 = <<10-6=4>>4 more $10 bills than Mandy. #### 4