Zachary has a smart phone data plan that costs $40 per month that includes 10 GB of data, but will charge an extra $10 per GB over the included amount. How much would Zachary have to pay in a month where he used 3 GB over the limit? How much would Zachary have to pay in a month where he used went over by x GB?

a. $70

b. $(40 + 10x)

Step-by-step explanation:

The standard cost of the charges is $40 per month but an extra $10 per GB over the included amount.

a. Firstly the cost for a month in which he uses 3GB over the limit

we have a standard of $40, then he has to pay $10 per GB for the 3GB over the limit.

Thus the cost of the 3GB is $10 * 3 = $30

The total cost for using 3GB above the limit would be $40 + $30 = $70

b. For using x GB above the limit

He has to pay $10 per each GB above the limit

Thus, the amount to be paid for x GB above the limit would be x * $10 = $10x

So the total amount to be paid would be the base fee plus over the limit fee= $(40 + 10x)