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
[tex]x = 25 + y\\8x = 0.80 + 10y[/tex]
We substitute the first equation in the second one:
[tex]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[/tex]
Thus, the cost of an eraser is 99.6 cents.
On the other hand:
[tex]x = 25 + 99.6\\x = 124.6[/tex]
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.
