maya purchased a prepaid phone card for $25.00. Calls cost 25 cents a minute using this card. the credit, C (in dollars), left o
n the card after it is used for x minutes calls is given by the following. how much credit is left on the card after maya uses it for 20 minutes of calls?
If we say that the prepaid phone card has 25 minutes on it since Maya paid 25 dollars for it. We can multiply 25 times 4 which equals 1 dollar per 4 minutes. Then, we can divide 20 by 4 to get 5 which means that she used 5 dollars of call time. We can now subtract 25-5 and we get 20. This tells us that there is 20 dollars left on the card.
