Question

A prepaid phone card has a balance of $22.40 remaining. If calls are $0.035 per minute, which equation represents the number of minutes, m, you may talk using the card?

Answer 1

The equation that represents the number of minutes that Imay talk using the card is
`m =28.571\cdot C`.

Explanation:

From statement we know that balance (
`C`), measured in US dollars, is directly proportional to remaining call time (
`m`), measured in minutes. That is:

`C \propto m`

`C = k\cdot m` (Eq. 1)

Where
`k` is the proportionality ratio, measured in US dollars per minute.

If we know that
`k = 0.035\,(USD)/(min)`, then the equation is:

`C = 0.035\cdot m`

Now we clear remaining call time within equation:

`m =28.571\cdot C`

The equation that represents the number of minutes that Imay talk using the card is
`m =28.571\cdot C`.