I’m assuming you are talking about number four. If you look at the line it provides you, the slope is -.5 and the intercept is zero. So all you have to do is rewrite the equation but subtract four from the right side and it will be parallel.
70 x P = 63
P=63/70 = 0.9
Since P is 1-the discount
1-discount= 0.9
discount is 0.1, or 10 %
