Problema Solution
Arnold is about to go on a 500-mile car trip. His mechanic recommends that he buy a special highway engine oil that will save him 50 cents in gas for every 25 miles of the trip. This new oil, however, will cost $20. Is it worthwhile for Arnold to buy the oil if he has a coupon for $4 dollars off the price
Answer provided by our tutors
For 500 mile trip without the special oil Arnold will need: 500x, where x is the cost for gas per mile
For 500 mile trip with the special oil Arnold will need: 500x - (500/25)*0.50 + 20 - 4 = 500x + 6
Since 500x + 6 > 500x the special oil is not worthwhile.