lesson on word problems

Question

John needs help with math. His parents hire a tutor for him. The tutor charges $20.00 for 30 minutes.

What is the cost for 90 minutes with the tutor?

Answer 1

if you have to ask, you can't afford him, her, them or whatever the latest PC pronoun is

$20 for 30 minutes

$60 for 90 minutes

30/90 = 1/3 = 20/60

ratio of time = corresponding ratio of rate charged

90 minutes is 3 times as long, so the cost is 3 times as much: 3x$20 = $60