Question

Analyze the cost purchase of two cars both four years old. One car costs Php 130,000 and gets 20 kilometers a gallon. The other costs Php 145,000 and gets 35 kilometers a gallon. Which car is the better buy if you plan to keep it for two years?
Represent the answer graphically and algebraically.

Answer 1

Total cost = price of car + price of gas for 2 years
Let k be total kilometers driven over 2 years
Let g be price of 1 gallon of gas
Car 1:
Cost = 130,000 + kg/20
Car 2:
Cost = 145,000 + kg/35

145,000 + kg/35 < 130,000 + kg/20
kg/35 - kg/20 < -15,000
4kg/140 - 7kg/140 < -15,000
-3kg < -2,100,000
kg > 700,000
k > 700,000/g

Therefore Car2 is the better buy if you plan on driving more than (700,000/g) kilometers