Question

Mr. Martin is giving a math test next period. The test, which is worth 100 points, has 29 problems. Each problem is worth either 5 points or 2 points. Write a system of equations that can be used to find how many problems of each point value are on the test.

Let x be the number of questions worth 5 points and let y be the number of questions worth 2 points.

Answer 1

There are 14 problems worth 5 points and 15 problems worth 2 points.

Explanation:

x - the number of 5 points worth problems

y - the number of 2 points worth problems

The test has 29 problems.

x+y=29x+y=29

The test is worth 100 points.

5x+2y=100

The system of equations:

x+y=29

5x+2y=100

The solution:

x+y=29 ∣×(−2)

5x+2y=100

Substract −2x−2y=−58 from 5x+2y=100

−2x−2y=−58

5x+2y=100

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3x=42

3x/3 = 42/3

x=14

x+y=29

14+y=29

14+y-14 = 29 - 14

y=15

There are 14 problems worth 5 points and 15 problems worth 2 points.