Lena purchased a prepaid phone card for $15. Long distance calls cost 24 cents a minute using this

[math_celebrity]

Lena purchased a prepaid phone card for $15. Long distance calls cost 24 cents a minute using this card. Lena used her card only once to make a long distance call. If the remaining credit on her card is $4.92, how many minutes did her call last?

Figure out how many minutes Lena used:
Lena spent $15 - $4.92 = $10.08.

Now determine the amount of minutes
$10.08/0.24 cents per minute = 42 minutes