Answer:
The answer would be A) (-69, 15)
Solution:
Finding 1st and 2nd
m = (y2 - y1)/(x2 - x1)
m = (15 - 3 )/(6 - 3)
m = 12/3
y = 4x + b
3 = 3(3)+b
3=9+b
-9 -9
-6=b
Finding 3rd
repeat the above process for 1 and 2, so now use 2 and 3 in the equation.
m = -9/3
m=-3
y=-3x+b
15=-3(6)+b
b=-3
Step 2