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?

Question

Zoe Powell

Mathematics

21 September, 17:56

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?

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Answers (1)

Know the Answer?

Kaylah · Answer 1

Set up a system of equations. One equation will be for the number of problems and the other equation will be for the time.

2a + 5g = 90

a + g = 27

To solve multiply the second equation by - 2

2a + 5g = 90

-2a - 2g = - 54

Now add the equations

3g = 36

g = 12

a + g = 27

a = 27-12

a = 15

15 algebra problems