This is a simple enough question, well at least i assume it should be, but it's stumping me somewhat, how they've derived the answer that they put.

can someone walk me through it? I dunno where i may be going wrong... I've been practicing similar questions with ok enough luck but this one, i dunno..

The question reads as follows:

Given that y=x^3 - 12x, find the slope of the curve at the point P, where P = (1, -11). (Find the gradient of the secant slope)