Answer:
19 miles
Explanation:
Let m represent the number of miles traveled. Then the delivery charge is ...
charge = $5.00 + $0.15·m
You want to find the value of m that makes the charge by $7.85, so you want the solution to ...
$7.85 = $5.00 +$0.15·m
$2.85 = $0.15·m . . . . . . . . . subtract $5 (this gives the mileage charge)
$2.85/$0.15 = m = 19 . . . . . divide by the coefficient of m
The number of miles traveled is 19.