help this is making my head spin

Question

Heather purchased a prepaid phone card for
$30
. Long distance calls cost
17
cents a minute using this card. Heather used her card only once to make a long distance call. If the remaining credit on her card is
$23.37
, how many minutes did her call last?

Answer 1

30 - 0.17*N = 23.27 where N is the number of minutes of the long distance phone call.

 

30 - 23.37 = 0.17*N

 

6.63 = 0.17* N

 

663 = 17*N

 

N = 663/17 = 39