I think there are flaws in your question which includes grammatical errors. Below is probably what you intended:
Melissa purchased a prepaid phone card for $15. Long distance calls cost 17¢ a minute using this card. Melissa used her card only once to make a long distance call. If the remaining credit on her card is $9.39, how many minutes did her call last
Answer: Melissa's long distance call lasted for exactly 33 minutes.
Step-by-step explanation:
Since the prepaid call card she purchased costs $15 and the balance after making the long distance call was $9.39, then the amount that was spent by Melissa for making the call will be obtained by subtracting the balance after making the long distance call from the initial cost of the prepaid call card. That is:
$15.00 - $9.39
= $5.61¢
Therefore, Melissa spent $5.61 to make the long distance call out of the $15 that was initially on the prepaid call card.
Now, if it costs 17¢ to make a long distance call for one minute, then we can find the time or period that Melissa spent on the long call that made her to spend $5.61 of the prepaid call card. We can achieve this by simply dividing the amount spent on the card by the amount it costs to make a long distance call for a minute.
Since 100¢ make 1 dollar, 17¢ will be equal to 17/100 = $0.17
Then:
$0.17 -------- 1 minute
$5.61 -------- ? minutes
5.61/0.17 × 1
= 33 minutes (This was Melissa's call period)
Therefore Melissa's long distance call lasted for exactly 33 minutes
