Question

The cost of a pencil is 25 cents more than the cost of an eraser. If the cost of 8 pencils is 0.80 more than the cost of 10 erasers, find the cost of each.

Answer 1

For this case we propose a system of equations:

x: Let the variable representing the cost of a pencil

y: Let the variable representing the cost of an eraser

`x = 25 + y\\8x = 0.80 + 10y`

We substitute the first equation in the second one:

`8 (25 + y) = 0.80 + 10y200 + 8y = 0.80 + 10y\\200-0.80 = 10y-8y\\199.2 = 2y\\\frac {199.2} {2} = y\\y = 99.6`

Thus, the cost of an eraser is 99.6 cents.

On the other hand:

`x = 25 + 99.6\\x = 124.6`

Thus, the cost of a pencil is 124.6 cents.

Answer:

The cost of an eraser is 99.6 cents.

The cost of a pencil is 124.6 cents.