how many miles must one drive to justify using plan b

Question

plan a is 30 dollars per day and 18 cents per mile

plan b is 50 dollars per day with free unlimited mileage

Answer 1

m represents the number of miles

 

a: 30 + 0.18m

b: 50

 

b < a

50 < 30 + 0.18m

20 < 0.18m               subtract 30 from both sides

111.11 < m               divide both sides by 0.18

 

plan b becomes a better deal after 111.11 miles.