First, we need to know how much is saved per month. We know that the old monthly bill was $112, and that the new one is $88. By taking the difference, we will find the savings.
$112-$88=$24
So, the manager saves $24 per month.
One month goes by, and the manager saves $24.
24*1=24
Two months go by, and the manager has saved $48.
24*2=48
X months go by, and the manager has saved $650 or more.
24*X=650
Solve for X
X=650/24
650/24 is a little over 27, so we put 27 into the equation for X and see what we get.
24*27=648
In 27 months, the manager will have saved just under $650, so in 28 months, he will have saved the cost of the copier.
