What value is a discontinuity of quantity x squared plus 3 x minus 4 divided by quantity x squared plus x minus 12

(x² + 3x + 4) / (x² + x - 12) 

Note that you can't divide by zero, and discontinuities are a result of that. We are looking for: 
x² + x - 12 = 0 
(x + 4)(x - 3) = 0 
x = 3, -4 

a. is one of those values, and is the answer.