John builds a model rocket that can travel 500 ft in the air. He builds a second rocket that can travel twice as high. What is the combined height of the two rockets?

How high does the second rocket go? ** The second rocket goes 500*2=

<<500*2=1000>>1000 feet What is the combined height of the two rockets? ** So the total height is 500+1000=<<500+1000=1500>>1500 feet #### 1500 Scarlet saved $80 to spend on jewelry. She bought a pair of earrings that cost $23. Then, she bought a necklace that cost $48. How much of her savings have left? How much did Scarlet spend? ** Scarlet spent $23 + $48 = $<<23+48=71>>71 for the jewelry. How much of her savings have left? ** So, She was left with $80 - $71 = $<<80-71=9>>9 on her savings. #### 9 Anya has 4 times as many erasers as Andrea. If Andrea has 4 erasers, how many more erasers does Anya have than Andrea? How many erasers does Anya have? ** Anya has 4 x 4 = <<4*4=16>>16 erasers. How many more erasers does Anya have than Andrea? ** Thus, Anya has 16 - 4 = <<16-4=12>>12 more erasers than Andrea. #### 12 Jamal bought 4 half dozen colored crayons at $2 per crayon. What was the total cost of the crayons that she bought? How many items are in a half dozen? ** Since a dozen has 12 items, a half dozen has 1/2*12=<<6=6>>6 items. How many crayons did Jamal buy? ** Since Jamal bought four half dozen colored crayons, he bought 4*6 = <<4*6=24>>24 colored crayons. How much did Jamal pay for the crayons? ** If each crayon's cost was $2, Jamal paid $2*24 = $<<2*24=48>>48 for all the crayons he bought. #### 48 Harry is joining a marathon that's why he practices and varies his workouts from day to day. He ran 10 meters per hour on Monday. From Tuesday to Thursday he ran 50% faster than on Monday. Then on Friday, he ran 60% faster than he ran on Thursday. How fast did Harry run on Friday? How fast did Harry run on Tuesday to Wednesday? ** Harry ran 10 x 50/100 = <<10*50/100=5>>5 meters per hour faster on Tuesday to Wednesday. How fast did Harry run on Tuesday to Thursday? ** So he ran 10 + 5 = <<10+5=15>>15 meters per hour from Tuesday to Thursday. How fast did Harry run on Friday? ** Then on Friday, he ran 15 x 60/100 = <<15*60/100=9>>9 meters per hour more. How fast did Harry run on Friday? ** Therefore, he ran 15 + 9 = <<15+9=24>>24 meters per hour on Friday. #### 24 The length of a rectangle is four times its width. If the area is 100 m2. what is the length of the rectangle? Define a variable ** Let L be the length and W be the width of the rectangle. How many meters is the length? ** Hence L = 4* W How many meters is the area? ** We now use the area to write 80 = L * W How many meters is the area? ** Substitute L by 4 W in the equation above 80 = 4*W × W = 4 W^2 How many meters is the length? ** Solve for W and find L How many meters is the area? ** 4 W^2 = 100 How many meters is the width? ** W^2 = 25, W = 5 and How many meters is the length? ** L = 4*5 = <<4*5=20>>20 m #### 20 A shop sold 29 bags of potatoes in the morning. In the afternoon, the shop sold 17 bags of potatoes. If each bag of potatoes weighs 7kg, how many kilograms of potatoes did the shop sell for the whole day? How many bags of potatoes did the shop sell in total? ** They sold in the morning and afternoon for a total of 29+17 = <<29+17=46>>46 bags How many kilograms of potatoes did the shop sell in total? ** Each bag weighs 7kg so 46 bags weigh 46*7kg = 322kg #### 322 It's Yvette's turn to treat herself and her three best friends to a round of ice cream sundaes. Alicia orders the peanut butter sundae for $7.50. Brant orders the Royal banana split sundae for $10.00. Josh orders the death by chocolate sundae for $8.50 and Yvette orders the cherry jubilee sundae for $9.00. She leaves her waiter a 20% tip. How much will her final bill be? How much did Yvette spend on ice cream sundaes? ** Yvette spent 7.50+10+8.5+9 = $<<7.50+10+8.5+9=35.00>>35.00 on ice cream sundaes How much did Yvette leave as a tip? ** Her bill comes to $35.00 and she leaves a 20% tip for the waiter so that's 35*.20 = $7.00 How much did Yvette's final bill end up being? ** The bill was $35.00 and she added a $7.00 tip for a total of 35+7 = $<<35+7=42.00>>42.00 #### 42 Tom swims for 2 hours at a speed of 2 miles per hour. He then runs for half the time at 4 times the speed. How many miles did he cover? How many miles did Tom swim? ** He swam 2*2=<<2*2=4>>4 miles How many hours did Tom run? ** He ran for 2/2=<<2/2=1>>1 hour How fast did Tom run? ** His running speed was 2*4=<<2*4=8>>8 mph How many miles did Tom run? ** So he ran 8*1=<<8*1=8>>8 miles How many miles did Tom cover? ** So his total distance was 8+4=<<8+4=12>>12 miles #### 12 Anna, Alison, and Jeff collect stamps. Anna had 37 stamps in her collection, Alison had 28 stamps in her collection, and Jeff had 31 stamps in his collection. Alison gave Anna half of her collection in exchange for a novel, and then Anna traded Jeff two bluebird stamps for one mountain stamp. How many stamps did Anna have in the end? How many stamps did Alison give Anna? ** Alison gave Anna 1/2 * 28 = 28/2 = <<1/2*28=14>>14 stamps. How many stamps does Anna have in the end? ** Adding Alison’s stamps to Anna’s collection means Anna has 14 + 37 = <<14+37=51>>51 stamps. How many stamps did Anna have in the end? ** Then Anna traded Jeff 2 stamps, so she had 51 - 2 = <<51-2=49>>49 stamps. How many stamps did Anna have in the end? ** Anna got 1 stamp back in the trade, so she had 49 + 1 = <<49+1=50>>50 stamps in the end. #### 50