This is in slope-intercept form, so you can think of it as being y=mx+b. Invert m (the slope) and flip its sign, and then substitute the x and y values in and solve for b. The answer is y=7/2x-20.
<h2>Here we go ~ </h2>
According to given figure,
[ By linear pair ]
now, we can see that :
[ By Exterior angle property of Triangle ]