It is very easy to graph these two equations. You have the y-intercept for the first equation which is -2, and the slope -1/1. The y-intercept for the second equation is 4, and the slope is 2/1.
When you graph these two equations, you will see that they intersect at the point (-2,0); this is the answer.
First you need to find the amount of money the discount decreased. 10(0.2)=2 Then, in order to find the sale price you need to subtract the discount price from the original price of the burger. 10-2=8 Answer: $8