If Rick’s Automotive charges $50 plus $15 for each (15-min) unit of time when making a road call. Twin City Repair charges $70 plus $10 for each unit of time. Under what circumstances would it be more economical for a motorist to call Rick’s? show all work

Answer 1

for charges,

r = 50 + 15m for m units
t = 70 + 10m

you want

r < t
50 + 15m < 70 + 10m
5m < 20
m < 4

so, if the call lasts less than an hour (4 units of 15 min. each) it will be cheaper to call Rick.