1. **State the problem:** Calculate the average hourly cost of labor given the total job time and labor charges. 2. **Calculate total parts cost:** - Convert hose lengths from inches to feet: 30 inches = $\frac{30}{12} = 2.5$ feet, 24 inches = $\frac{24}{12} = 2$ feet. - Cost of 1 inch hose: $2.5 \times 1.25 = 3.125$ - Cost of 1 inch hose: $2 \times 1.35 = 2.7$ - Hose clamps: $2 \times 0.84 = 1.68$ (for each size, total 4 clamps $= 1.68 \times 2 = 3.36$) - Hose clamps (4 at $0.98$ each): $4 \times 0.98 = 3.92$ - Thermostat with gasket: $5.65$ - Pressure cap: $4.50$ - Upper hose: $11.44$ - Lower hose: $16.53$ 3. **Sum parts cost before tax:** $$3.125 + 2.7 + 3.36 + 3.92 + 5.65 + 4.50 + 11.44 + 16.53 = 50.225$$ 4. **Calculate sales tax (7% on parts):** $$0.07 \times 50.225 = 3.51575$$ 5. **Total parts cost including tax:** $$50.225 + 3.51575 = 53.74075$$ 6. **Calculate total labor charge:** $$39.50 + 20.00 + 10.00 + 0 = 69.50$$ 7. **Total job time:** $3.5$ hours 8. **Calculate average hourly labor cost:** $$\text{Average hourly cost} = \frac{69.50}{3.5}$$ 9. **Simplify fraction:** $$\frac{69.50}{3.5} = \frac{\cancel{69.50}}{\cancel{3.5}} = 19.857142857...$$ 10. **Round to nearest cent:** $$19.86$$ **Final answer:** The average hourly cost of labor is **19.86**.