Question: Peter has 20 books. He has read 40% of them. His brother has read 10% of them. How many more of these books has Peter read than his brother?
Answer: Peter has read 8 of these books because 20 x .4 = 8. His brother has read 2 of these books because 20 x .1 = 2. Peter has read 6 more books than his brother because 8 - 2 = 6. The answer is 6.

Question: The largest room in Mrs. McAvoy's house is 45 feet wide and 30 feet long. The smallest room in that same house is 15 feet wide and 8 feet long. What is the difference in area between the largest room and the smallest room?
Answer: The area of the largest room is 45 ft x 30 ft = 1350 sq ft. The area of the smallest room is 15 ft x 8 ft = 120 sq ft. The difference between the two is 1350 sq ft - 120 sq ft = 1230 sq ft. The answer is 1230.

Question: A sack of rice, which is 50 kilograms, costs $50. If David sells it for $1.20 per kilogram, how much will be his profit?
Answer: David's revenue for the 50 kilograms of rice is $1.20 x 50 = $60. So, his profit is $60 - $50 = $10. The answer is 10.

Question: Debbie works at a post office packing boxes to mail. Each large box takes 4 feet of packing tape to seal, each medium box takes 2 feet of packing tape to seal, and each small box takes 1 foot of packing tape to seal. Each box also takes 1 foot of packing tape to stick the address label on. Debbie packed two large boxes, eight medium boxes, and five small boxes this afternoon. How much tape did she use?
Answer:
Debbie used 4 * 2 = 8 feet of tape for the large boxes. She used 2 * 8 = 16 feet of tape for the medium boxes. She used 1 * 5 = 5 feet of tape for the small boxes. There were 2 + 8 + 5 = 15 boxes in all. She used 1 * 15 = 15 feet of tape for the address labels. Thus, she used 8 + 16 + 5 + 15 = 44 feet of tape in all. The answer is 44.