Answer:
Manny should keep the old car since he gets to spend less on it in three years compared to getting the fuel-efficient car.
Explanation:
Step 1:
Number of miles Manny commutes per week = 160
Cost per gallon of gasoline. = $2.9
Mileage of old car = 20 miles per gallon
Maintenance cost per year of old car = $760
Cost of new car = $7000
Maintenance cost per month of new car = $10
Mileage of new car = 31 miles per gallon
Step 2:
There are 52 weeks in a year. Total distance Manny will commute in 3 years = 160 * 52 * 3 = 24960 miles
Maintenance cost of old car in 3 years = $760 * 3 = $2280
Maintenance cost of new car in 3 years = $10/month * 12 months * 3 = $360
Gasoline usage of old car in 3 years = 24960 miles/20 miles per gallon = 1248 gallons
Cost of gasoline = 1248 * $2.9 = $3619.2
Gasoline usage of new car in 3 years = 24960 miles/31 miles per gallon
Cost of gasoline = $2.9 * 24960 miles/31 miles per gallon = $2334.97 or approximately $2335
Step 3:
Total expenditure on old car for 3 years = $2280 + $3619.2 = $5899.2
Total expenditure on new car for 3 years = $7000 + $360 + $2335 = $9695
From the calculations above, Manny will spend $5899.2 on the old car compared to $9695 on the new car in three years.
Therefore, Manny should keep the old car since he gets to spend less on it in three years compared to getting the fuel-efficient car.