The parabola $y = ax^2 + bx + c$ is graphed below. Find $a+b+c$. (The grid lines are one unit apart.)
The parabola goes through (-5,0), (0,3), and (4,0).
c = 3
a(-5)^2 +b(-5) + 3 = 0
a(4)^2 + b(4) +3 = 0
25a - 5b = -3 → 100a - 20b = -12
16a + 4b = -3 → 80a + 20b = -15
180a = -27
a = -27/180 = -3/20
16 (-3/20) + 4b = -3
4b = -3 + 48/20
b = -3/4 + 48/80= -3/20
a + b + c = 2 * ( -3/20 ) + 3 = -6/20 + 60/20 = 54/20 = 27 / 10
+948 
