By your cell phone contract, you pay a monthly fee plus ${\$0.04}$ for each minute you spend on the phone. In one month, you spent $220$ minutes over the phone, and had a bill totaling ${\$24.80}$. Let $x$ be the number of minutes you spend on the phone in a month, and let $y$ be your total cell phone bill for that month. Use a linear equation to model your monthly bill based on the number of minutes you spend on the phone.

1. This line’s slope-intercept equation is .
2. If you spend $200$ minutes on the phone in a month, you would be billed .
3. If your bill was ${\$34.40}$ one month, you must have spent minutes on the phone in that month.