The maximum number of hours he can afford is 3 hours
Here, we want to get the number of hours Fred can afford to have the plumber work
From the question, we have a fixed $85 charge
Let the number of hours worked be h
Thus, we have an equation where the cost of hiring is c
We have this as;
Now, from the question, we are told that the charge is based on every half-hour
We can now have;