Question

A phone service offers a data plan with a $25 monthly fee and charges $10 per gigabyte download.

Answer 1

25 + 10x < = 75 <== ur inequality
10x < = 75 - 25
10x < = 50
x < = 50/10
x < = 5 <== solution

Answer 2

The correct answer is:

At most 5.

Explanation:

The monthly fee is $25 and the charge for data is $10 per gigabyte.  This means that the total monthly charges will depend on the number of gigabytes; this makes the gigabytes the independent variable.  We use x to represent the independent variable.

Since data is $10 per gigabyte, and x is the number of gigabytes, this gives us 10x.  We add to that the monthly fee of $25, for 10x+25.

We want to know how much they can download and pay at most 75; this means less than or equal to, and gives us the inequality

10x+25 ≤ 75

To solve this, subtract 25 from each side:

10x+25-25 ≤ 75-25

10x ≤ 50

Divide both sides by 10:

10x/10 ≤ 50/10

x ≤ 5

The maximum number of gigabytes that can be downloaded for this cost is 5.