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.
To find out how much more it rained, you subtract 1 1/4 or 1.25 and 3/5.
So you get 1.25-.6, which is .65 or 13/20 inches.
Hope this helps.
