Step-by-step reasoning process: There are 15 + 10 = 25 students in the class. 375 books were divided equally among them for a total of 375 / 25 = 15 books each. 15 girls will get a total of 15 * 15 = 225 books.
[Q & A] The question is There are 15 girls and 10 boys in Ms. Smith's class. She divided 375 books equally among them. How many books did all the girls get combined?
The answer is 225

Step-by-step reasoning process: On Mondays, he walks 6 miles at 2 miles per hour, for a length of 6 / 2 = 3 hours. On Wednesdays, he walks 6 miles at 3 miles per hour, for a length of 6 / 3 = 2 hours. And on Fridays, he runs 6 miles at 6 miles per hour, for a length of 6 / 6 = 1 hour. The combined total time he spends exercising in a week is 3 + 2 + 1 = 6 hours.
[Q & A] The question is Jonathan enjoys walking and running for exercise, and he has three different exercise routines. On Mondays, he walks at 2 miles per hour. On Wednesdays, he walks at 3 miles per hour. And on Fridays, he runs at 6 miles per hour. On each exercise day, he travels 6 miles. What is the combined total time, in hours, he spends exercising in a week?
The answer is 6

Step-by-step reasoning process: If one intersection has 4 crosswalks, with 20 lines per crosswalk, there are 20 * 4 = 80 lines in all the crosswalks per intersection. If there are 5 intersections, the total number of lines in all the intersections is 80 * 5 = 400 lines.
[Q & A] The question is While driving up a road, Philip passed through 5 intersections. 4 crosswalks marked each intersection with a total of 20 lines per crosswalk. Calculate the total number of lines of the crosswalks in the five intersections.
The answer is 400

Step-by-step reasoning process: Let x be David's age. Yuan is seven years older than David, 7 + x = Y years. Yuan is also twice David's age, 2 * x = Y years. Since these two equations equal the same thing, we can write: 7 + x = 2 * x. Subtracting x from both sides we get 7 = x, so David is 7 years old.
[Q & A]
The question is Yuan is 7 years older than his brother David and twice his age. How old is David?
The answer is 7