Thats not the whole answer, you didnt attach the graph but what you need to do is find the y-intercept and put that into b and theres your equation. The y-intercept(B) represents the initial money that joe had in his savings the 2.50x part or the slope is the money that he states he can add each week.
slope is how much money joe adds to his account savings each week
the y intercept is the money he had before he started waiting
for the equation the slope is $2.50 and the y intercept is where the line hits the y axis but because you don't have a graph I don't know how to help you with this part, maybe someone else can!
To find the average rate of change, evaluate the function at the given points. Evaluate the difference of the function at the given points. Divide the difference of the function at the given points with the difference of the given points.
I just listed the two equations out and the answer just popped out. The trick to this is just thinking about two numbers that obviously both below 13 that add up to it. 6 and 7 is the solution.
