Question

On Chatty Cathy’s cell phone plan she pays for minutes used plus a fixed monthly charge. For 500 minutes she pays $12 plus the fixed charge. For 1500 minutes used she pays $30 plus the fixed charge.

If her total monthly bill was $86.50 for 1750 minutes used, what is her monthly fixed charge?
A)
$50.50
B)
$54.00
C)
$55.00
D)
$56.50