Phone card word problem

by constance
(tallahassee)

Elsa purchased a phone card for $25. Long distance cost .11 a minute using this card. Elsa used her card only once to make a long distance call. If the remaining credit on her card is $21.59, how many minutes did her call last.

Solution

Elsa spent 25 minus 21.59

25 - 21.59 = 3.41


Let y be the amount of minutes

0.11 × y = 3.41


Divide both sides by 0.11


0.11y / 0.11 = 3.41 / 0.11

y = 31

Her call lasted 31 minutes.