Question

if it cost $85 for one person to have a cell-phone, and adding a line on increases the bill to $105, how much money would each person save with the shared account

Answer 1

$85 is the cost of each cell phone for one person. By adding another line which brings the bill to $105.

If each person bought a cell phone individually, they would each have to pay $85 each. But with a shared bill for two cell phone lines of $105, they would have to each pay $52.5 which is half the total of $105 for two lines on a shared line. So the difference between $85 on individual lines and $52.5 paid by each person on a shared line totalling $105 for both, is the answer, $30.25