Question

For her cell phone plan Heather pays $30 per month plus $0.05 per text. She wants to keep her bill under $60 per month. What inequality represents how many texts Heather can send each month while staying within her budget?

Answer 1

The monthly cost is `30+0.05n` if we call the number of texts `n`.
Heather wants to keep this less than `60`, so the inequality is:

`30+0.05n<60`

Explanation:

Note that we can also subtract `30` from each side:

`0.05n<30`

We can also divide both sides by `0.05`:

`n<600`

This is the most useful inequality, since it tells Heather she needs to send fewer than 600 texts per month, or about 20 per day.