There is a mandatory fixed rate of $ 35 that Raphael will have to pay once the service call has been made. This fixed rate is the constant.
The per hour rate is $20. Suppose the machine took "x" hours to get fixed. Then the variable part of the repair cost will be .
Thus, Repair Cost=Fixed Rate Cost+Variable Cost
Or, where
is the total repair cost. Thus, if Raphael ‘s machine took 2 hour to fix, the repair cost is:
dollars.
Therefore, the last option is the correct option.