Add like terms to get -4c = 3. divide by ,-4 each side so c = -3/4
Always
Anytime point A is on line BC, AB+BC=BC
You can find the perimeter by just counting the distance of every line segment all around the shape since they have vertical and horizontal slopes.
A) 6² and 7² , 36 and 49 not this one
B) 7²=49 and 8²=64 not this one
C) 8²=64 and 9²=81 , so 8 and 9, correct answer