Answer:
3 hours
Step-by-step explanation:
A plumber charges a diagnostic check of $65-this is also like a flat fee meaning, 0 hours=$65.
if you have a total of $320 in your wallet and the plumber charges $85 per hour, you simply do the following:
320-80=$240 remaining after the diagnostic check. To solve for how many hours he can work before you loose all your money:
$240-$85=3