Answer:
99+45x the technician worked on your computer for 3.5 hours
Explanation:
256.50-99=157.50 that is the total cost of labor as you take the cost of the parts out of the equation. 157.50/45=3.5 as that is how much labor costs so we now know how long it took him to work on the computer. we don't include the total cost into the equation as this would be a final answer and we need the expression to get the final answer. the expression would be (cost of parts)-(cost of labor)(hours worked)=(total cost)