Explanation:
10h represents the cost of $10 per hour for h hours, where h is some positive whole number. We tack on the extra $5 to add on the cost of gas.
For example, if the babysitter works for 7 hours, then h = 7. It leads to a cost of 10h+5 = 10*7+5 = 70+5 = 75. The total cost is therefore $75 in this case.