Question

One smartphone plan costs $52 per month for talk and messaging and $8 per gigabyte of data used each month. A second smartphone plan costs $82 per month for talk and messaging and $3 per gigabyte of data used each month. Let c represent the total cost in dollars and d represent the amount of data used in gigabytes.

The system of equations {c=52+8dc=82+3d can be used to represent this situation.
How many gigabytes would have to be used for the plans to cost the same? What would that cost be?

Both plans would cost $
if
gigabytes of data are used.

Answer 1

a) 6 gigabytes

b) $100

Explanation:

Let c represent the total cost in dollars and d represent the amount of data used in gigabytes.

For the first smartphone

One smartphone plan costs $52 per month for talk and messaging and $8 per gigabyte of data used each month.

Equation =

c = 52 + 8d

For the Second smartphone

A second smartphone plan costs $82 per month for talk and messaging and $3 per gigabyte of data used each month.

Equation =>

c = 82 + 3d

How many gigabytes would have to be used for the plans to cost the same?

We would equate both cost to each other

52 + 8d = 82 + 3d

Collect like terms

8d - 3d = 82 - 52

5d = 30

d = 30/5

d = 6

Therefore,

a) The number of gigabytes for the cost of both Smartphone data plans to be the same = 6 gigabytes.

b) The cost of both plans if 6 gigabytes is used =>

c = 52 + 8d

c = 52 + 8 × 6

c = $100