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?
Let's think: 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.. The answer is: 225.

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?
Let's think: 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.. The answer is: 6.

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.
Let's think: 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.. The answer is: 400.

Yuan is 7 years older than his brother David and twice his age. How old is David?
Let's think:
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.. The answer is: 7.