Question

4 pencils and 3 crayons are 20.9 inches. 5 pencils and 4 crayons are 26.5 inches. Each pencil is the same length as the other pencils, and each crayon is the same length as the other crayons. What is the length of 1 pencil? What is the length of 1 crayon?

Answer 1

The length of the pencils is 4.1 inches and for the crayons 1.5 inches

Explanation:

We can solve by means of a 2x2 system of equations, we have to:

let "x" be the length of the pencils

let "y" be the length of the crayons

4 * x + 3 * y = 20.9

5 * x + 4 * y = 26.5 => x = (26.5 - 4 * y) / 5

Replacing:

4 * (26.5 - 4 * y) / 5 + 3 * y = 20.9

21.2 - 3.2 * y + 3 * y = 20.9

-0.2 * y = 20.9 - 21.2

y = -0.3 / -0.2

y = 1.5

now for x:

x = (26.5 - 4 * 1.5) / 5

x = 4.1

This means that the length of the pencils is 4.1 inches and for the crayons 1.5 inches