Suppose that a and b are positive real numbers, and let
f(x) = ax if x = -4
f(x) = bx if x > -4
If f(-4)=-\frac{60}{13} and f(4)=3120, what is a+b?
a = 15/13, and b = 780, a+b = 781 2/13 or 10155/13
