Derek has $960 to buy his books for the semester. He spends half of that on his textbooks, and he spends a quarter of what is left on his school supplies. What is the amount of money Derek has left?

Amount spent on textbooks is 960/2 =

<<960/2=480>>480 dollars. Amount spent on school supplies is 480/4 = <<480/4=120>>120 dollars. Amount Derek has left 960-480-120 = <<960-480-120=360>>360 dollars. #### 360 A certain tree was 100 meters tall at the end of 2017. It will grow 10% more than its previous height each year. How long has the tree grown from 2017 until the end of 2019? At the end of 2018, the tree will grow 100 x 10/100 = <<100*10/100=10>>10 meters more. Thus, its height at the end of 2018 is 100 + 10 = <<100+10=110>>110 meters. At the end of 2019, the tree will grow 110 x 10/100 = <<110*10/100=11>>11 meters more. So, its height at the end of 2019 is 110 + 11 = <<110+11=121>>121 meters. Therefore, the tree has grown 121 - 100 = <<121-100=21>>21 meters. #### 21 Lisa and Carly go shopping together. Lisa spends $40 on t-shirts then spends half of this amount on jeans and twice this amount on coats. Carly spends only a quarter as much as Lisa on t-shirts but spends 3 times as much on jeans and a quarter of the amount Lisa spent on coats. In dollars, how much did Lisa and Carly spend in total? Lisa spends $40 on t-shirts / 2 = $<<40/2=20>>20 on jeans. She also spends $40 on t-shirts * 2 = $<<40*2=80>>80 on coats. So Lisa has spent a total of 40 + 20 + 80 = $<<40+20+80=140>>140. Carly spends $40 / 4 = $<<40/4=10>>10 on t-shirts. She also spends $20 per pair of jeans * 3 = $<<20*3=60>>60 on jeans. She then also spends $80 Lisa’s cost for coats / 4 = $<<80/4=20>>20 on coats. So Carly has spent a total of 10 + 60 + 20 = $<<10+60+20=90>>90. Lisa and Carly have therefore spent a total of 140 + 90 = $<<140+90=230>>230. #### 230 A small poultry farm has 300 chickens, 200 turkeys and 80 guinea fowls. A strange, incurable disease hit the farm and every day the farmer lost 20 chickens, 8 turkeys and 5 guinea fowls. After a week, how many birds will be left in the poultry? There are 300+200+80 = <<300+200+80=580>>580 birds in total Every day 20+8+5 = <<20+8+5=33>>33 birds are lost After a week which is 7 days, 33*7 = <<33*7=231>>231 birds would be lost There would be 580-231 = <<580-231=349>>349 birds left in the poultry #### 349 After tests in California, the total number of Coronavirus cases was recorded as 2000 positive cases on a particular day. The number of cases increased by 500 on the second day, with 50 recoveries. On the third day, the total number of new cases spiked to 1500 with 200 recoveries. What's the total number of positive cases after the third day? When 500 new cases were recorded after the tests, the total number of positive cases increased to 2000 cases + 500 cases = <<2000+500=2500>>2500 cases. With 50 recoveries, the total number of cases reduced to 2500 cases - 50 cases = <<2500-50=2450>>2450 cases. On the third day, with 1500 new cases, the total number of cases became 2450 cases + 1500 cases = <<2450+1500=3950>>3950 cases. If 200 people recovered from the virus, the total number of people with Coronavirus became 3950 cases - 200 cases = 3750 cases #### 3750 Caleb and his dad went fishing at the lake. Caleb caught 2 trouts and his dad caught three times as much as Caleb. How many more trouts did his dad catch compared to Caleb? Caleb’s dad caught 2 x 3 = <<2*3=6>>6 trouts. His dad caught 6 - 2 = <<6-2=4>>4 more trouts than Caleb. #### 4 Christina has 3 snakes. 1 snake is 2 feet long. Another snake is 16 inches long. The last snake is 10 inches long. How many inches are all of her snakes combined? The first snake is 24 inches because there are 12 inches in a foot. The snakes are 24+16+10= <<24+16+10=50>>50 inches long. #### 50 Madeline has 5 boxes with 24 crayons in each. She noticed that 5/8 of the crayons in the 2 boxes were not yet used. In the 2 other boxes, only 2/3 of the crayons were used while the last box was not entirely used. How many unused crayons did Madeline have? Two boxes of crayons have 24 x 5/8 = <<24*5/8=15>>15 unused crayons from each box. So, a total of 15 x 2 = <<15*2=30>>30 unused crayons are in the two boxes. For the other 2 boxes, there are 24 x 2/3 = <<24*2/3=16>>16 used crayons from each box. Hence, there are 24 - 16 = <<24-16=8>>8 unused crayons. So, a total of 8 x 2 = <<8*2=16>>16 unused crayons are in the other two boxes. Therefore, Madeline has a total of 30 + 16 + 24 = <<30+16+24=70>>70 unused crayons. #### 70 Yesterday, David and William were invited to a party. David broke 2 glasses, while his friend William broke 4 times the number of glasses David broke. How many glasses were broken? William broke 4 * 2 = <<4*2=8>>8 glasses. So, David and William broke 8 + 2 = <<8+2=10>>10 glasses. #### 10 Thor is 13 times older than Captain America. Captain America is 7 times older than Peter Parker, and Ironman is 32 years older than Peter Parker. How old is Ironman if Thor is 1456 years old? Captain America is 1456/13 = <<1456/13=112>>112 years old Peter Parker is 112/ 7 = <<112/7=16>>16 years old Ironman is 16 + 32 = <<16+32=48>>48 years old #### 48