Question

Sarah bought pencils and markers for school. She bought 3 times as many pencils as markers.

The pencils cost $0.15 each and the markers cost $0.30 each. In total, Sarah spent $7.50 on
pencils and markers. How many pencils did Sarah buy?
1. Define a variable for this problem. (For example: ' n = hours watching tv")
2. Create a model in words or in numbers that could solve this problem.
3. Solve the problem.

Answer 1

Sarah bought 30 pencils

Explanation:

1. Let define p, as the number of pencils bought, and m, as the number of markers bought.

2.

`0.15p+0.30m=7.50`

`p=3m`

3. Substitute p in the first equation to 3m since p=3m as defined.

`0.15(3m) + 0.30m=7.50\\0.45m+0.30m=7.50\\0.75m=7.50\\m=10`

plug m into equation p=3m to find the number of pencils bought

`p=3m=3(10)=30`