He has 3 hours to read because 8 - 3.5 - 1.5 = 3. He has 180 minutes to read because 3 x 60 = 180. He can read 1,800 words because 180 x 10 = 1,800.
The answer: 1800
Reverse engineering the question: Henri has 8 hours to watch movies and read. He watches one movie that is 3.5 hours and one movie that is 1.5 hours. He then decides to read. If he can read 10 words a minute, how many words does he read before his free time is up?

Ruel has a total of 4 x 10 = 40 stamps from the four books. He also has 6 x 15 = 90 stamps from the six books. Therefore, he has a total of 40 + 90 = 130 stamps.
The answer: 130
Reverse engineering the question: Ruel has four books of 10 stamps and six books of 15 stamps. How many stamps does Ruel have?

Three candy bars cost 25 x 3 = 75. Two pieces of chocolate cost 75 x 2 = 150. So, the total amount needed to buy those is 75 + 150 + 50 = 275. Since a quarter is equal to 25, therefore 275 / 25 = 11 quarters are needed.
The answer: 11
Reverse engineering the question: A snack machine accepts only quarters. Candy bars cost 25, each piece of chocolate costs 75, and a pack of juice costs 50. How many quarters are needed to buy three candy bars, two pieces of chocolate, and one pack of juice?

Since each chapter of the book has 40 pages, Mitchell had read 10 * 40 = 400 pages from the first ten chapters. After reading 20 pages of the eleventh chapter, the total number of pages that Mitchell had read is 400 + 20 = 420. The next two chapters that she read had 2 * 40 = 80 pages. In total, Mitchell read 420 + 80 = 500 pages of the book that day.
The answer: 500
Reverse engineering the question:
Studying for her test, Mitchell had read ten chapters of a book before 4 o'clock. When it clocked 4, Mitchell had read 20 pages of the 11th chapter of the book she was studying from. After 4 o'clock, she didn't read the remaining pages of chapter eleven but proceeded and read 2 more chapters of the book. If each chapter in the book had 40 pages, calculate the total number of pages that Mitchell had read altogether?