the equation in y=mx+b or slope intercept form is

y=2x-7

x represents the number of days it will take to pay the money back. -7 represent the amount of money you own in at the start and y represents the money you owe at a given time.

to graph this we can ask the question how much will I owe on day 0

If we set x to 0 and solve for y we get

y=2*0-7

y=-7

So our first point on the line is (0,-7) which is the y intercept

find the next point by asking, how much you will owe on day 1

set x equal to 1 and solve for y

y=2*1-7

y=-5

So our next point is 1, the number of days and -5 the amount of money still owed

(1,-5)

Here is the graph of the equation:

The x intercept represents the day when all the money has been paid back. (about 3.5 days)

the slope we know is 2 or 2/1. We get that from the y=mx+b equation. M=the slope and B=y intercept

our m value is 2 and our b value is -7