Question

Rob is a high school student taking both algebra and geometry. Last night he had 27 homework problems combined from the two classes, and he took a total of 90 minutes to do them. If each algebra problem took him 2 minutes and each geometry problem took him 5 minutes, how many algebra problems did he have for homework?

2
5
12
15

Answer 1

15 problems

Explanation:

Answer 2

15

Explanation:

Let x represent the number of algebra problems. Then the number of geometry problems was 27-x and the total working time was ...

2x +5(27 -x) = 90

-3x = 90 -135 . . . . subtract 135

x = -45/-3 = 15 . . . divide by -3

Rob had 15 algebra problems for homework.