Practice!

Sample Problem

Mark took half an hour to solve 5 math problems and 2 science problems. He took the same amount of time to do each math problem. If it took him 8 more minutes to solve each science than each math problem, how long did it take him to solve each math problem?

min

Solution

1 science problem takes 8 more minutes than 1 math problem

2 science problems take 16 more minutes than 2 math problems, so 2 science problems = 2 math problems + 16 minutes

We convert the time it takes to complete science problems into the time it takes to complete math problems so that everything is in terms of math problems.

5 math problems and 2 science problems = 5 math problems + 2 math problems + 16 minutes = 7 math problems + 16 minutes

Each math problem: (30 min-16 min)  ÷ 7 = 2 min

So the answer is 2 min.