The telephone company offers two billing plans for local calls, Plan One charges $31.00 per month for unlimited calls. Plan 2 charges $18.00 per month plus four cents per call. Using inequality to find the number of monthly calls for which Plan One is more economical than Plan 2. So we want Plan One to cost less or be less than Plan 2. So 31, the flat fee has to be less than or equal to. They'll be the same cost if they're equal to as $18.00 + 4 cents or .04 X. So we're going to start by subtracting the 18 and then we're going to divide by .04. I'm going to multiply the top and the bottom each by 100 just to make it easier. And then I'm going to do the division and the easy way to do the the division is to think about four goes into 13, how many times? And you tell me three with one leftover. So then I'd think about four goes into 10 because the one leftover with the zero and that would be two with two leftover and then four goes into the 20 or five. So if there were 325 calls or more made, plan one is more economical.