[Question]: 9 years from now, John will be 3 times as old as he was 11 years ago. How old is he now?
[Answer]: Let J represent John’s age. We have J + 9 = 3(j − 11). So, J + 9 = 3J − 33. So, 9 = 2J − 33. So, 42 = 2J. Which means that John’s age is J = 42 / 2 = 21.
So the answer is 21.

[Question]: Sally reads 10 pages of a book on weekdays and 20 pages on weekends. If it takes 2 weeks for Sally to finish her book, how many pages that book has?
[Answer]: Two weeks has 5 * 2 = 10 weekdays. Two weeks has 2 * 2 = 4 weekends. On weekdays, she reads 10 * 10 = 100 pages in total. On weekends, she reads 20 * 4 = 80 pages in total. So the book has 100 + 80 = 180 pages.
So the answer is 180.

[Question]: Jim has a pail with rocks in it. The average weight of a rock is 1.5 pounds. A local rock collector agrees to pay him $4 for every pound of rocks. If he makes $60 off the sale, how many rocks were in the bucket?
[Answer]:
There were 15 pounds of rocks in the bucket because 60 / 4 = 15. There were 10 rocks in the bucket because 15 / 1.5 = 10.
So the answer is 10.