The -5x is your slope and the 2 is your y-intercept. To graph you just have to make a dot at the 2 on the y line. Next you are going to go up 5 and to the left once. You do the exact opposite going down as well. That will give you a straight line.
Okay so this is very easy so basically count the value of each coin then subtract to get *gets a call* hello? *other person starts talking* I just want you to know that the answer is 4 *hangs up* *starts talking* that was weird anyways the answer is four give