Answer:
($0.22/mile)x + $40/day ≤ $84/day, where x is the miles/day
Explanation:
Let y be the cost for a day of car rental, including the mileage fee of $0.22/mile. Let x be the number of miles driven each day.
y = ($0.22/mile)x + $40
The total cost for 100 miles in one day would be = ($0.22/mile)(100 miles) + $40, or $62.
But we are restricted to a daily budget of $84/day. Since we need to spend $84/day or less, we can write an inequality:
($0.22/mile)x + $40/day ≤ $84/day
Let's solve for x for the case that y = $84, the upper limit of expense:
($0.22/mile)x + $40 = $84
x = ($84/day-$40/day)/($0.22/mile)
x = 200 miles
We may travel up to 200 miles/day to stay with the $84/day budget.