Answer:
$63.00
Step-by-step explanation:
Since you have sales tax, you would do a 10% sales tax for 15 dollar
10/100 = x/15
Therefore you will calculate x and 100 divided by 15 which would be 6.6 repeated
You would round to the nearest tenth and get 6.6 then you would add 56.4 as in the tip+ month airtime usage and get 63 dollars.