Please i need help

Question

The credit remaining on a phone card (in dollars) is a linear function of the total calling time made with the card (in minutes). The remaining credit after 32 minutes of calls is $24.88, and the remaining credit after 55 minutes of calls is $21.20. What is the remaining credit after 74 minutes of calls?

Answer 1

32 minutes, 24.88 credit left

55 minutes 21.20 credit left

74 minutes ? credit left, obviously <21.2

55-32= 23 minutes cost 24.88-21.20 = 3.68

3.68/23 = .16 = 16 cents per minute

74-55= 19 minutes. 19x.16 = 3.04

21.20-3.04 = $18.16 credit left after 74 minutes