Question

Keisha purchased a prepaid phone card for 25. Long distance calls cost 6 cents a minute using this card. Keisha used her card only once to make a long distance call. If the remaining credit on her card is 23.56 , how many minutes did her call last?

Answer 1

The prepaid card has an initial credit of $25

For long-distance calls, the cost is $0.06/min

After making a long-distance call the remaining credit is $23.56

To calculate the remaining credit you have to subtract the cost of the long-distance call to the initial credit on the card.

Let "x" represent the number of minutes the call lasted, then we can express the remaining credit on the card using the following expression:

`23.56=25-0.06x`

From this expression, we can calculate the number of minutes (x) that the call lasted.

First, pass "25" to the left side of the expression by applying the opposite operation to both sides of it, i.e. subtract 25

`\begin{gathered} 23.56-25=25-25-0.06x \\ -1.44=-0.06x \end{gathered}`

Second, divide both sides of the equation by -0.06 to determine the value of x:

`\begin{gathered} -(1.44)/(-0.06)=-(0.06x)/(-0.06) \\ 24=x \end{gathered}`

x= 24 → this indicates that the call lasted 24 minutes.