Do you use data on a cellphone? You may have a maximum amount of data you can use without having to pay more. Suppose a family data plan includes 10 gigabytes of shared data and costs $80 per month. Any additional data usage is billed at $15 per gigabyte. A certain family wants to spend at most $125 on their bill each month. You could use an inequality to find that the family can use at most 3 additional gigabytes of data. When else could you use an inequality to find a range of values?