Question

HELP !! PLEASE
There are two cellular phone companies that provide service to Plainview. Their monthly rates are below.
Panorama Phones
$20.00 a month for the first phone line
plus
$10.00 a month for each additional phone line

Simply Cellular
$40.00 a month for the first phone line
plus
$5.00 a month for each additional phone line

According to the graph below, for how many phone lines will the monthly charges from each cellular phone company be equal?