Answer:
u = 7
Step-by-step explanation:
Using the slope intercept formula:
[tex]\frac{y2 - y1}{x2 - x1} = slope[/tex]
Substitute our values from the points and the known slope:
[tex]\frac{-7 - 0}{8 - u} = -7[/tex]
Now we multiply both sides by (8 - u) to isolate the x:
(8-u) x [tex]\frac{-7}{8 - u}[/tex] = -7 (8 - u)
Next we add 56 to both sides:
-7 = -56 + 7u
Finish off by dividing both sides by 7:
7u = 49
u = 7
