First, we need to find how much she paid the whole year. 27,700-x=7900. If we subtract 7900 from each side and add x to each side, we get 19,800=x. Therefore, she paid $19,800 in rent the whole year. Since there are 12 months in a year, and each month she paid the same, she paid $1,650 in rent each year, for 19800/12=1650
The slope intercept form is y=mx+b, and b represents the y-intercept. In the given equation C=45t+100, 100 is the y-intercept. It represents the one-time fee to join the gym membership.