Answer:
98w +115(18-w)
Explanation:
The fees per credit hour at Westside are $98.
The fees per credit hour at Pinewood are $115.
The total amount of hours is 18, this means the hours at Westside plus the hours at Pinewood add up to 18.
The problem asks us to name "w" the credit hours at Westside, therefore, the credit hours at Pinewood would be "18 - w"
Combining this information, we have that the combined total amount he paid would be:
(Fee per hour at Westside)(hours at Westside) + (Fee per hour at Pinewood)(hours at Pinewood) = Total
⇒98w + 115(18 - w) = Total