Question

(t+3)(t-6)=0

Answer 1

do you know how to foil?

Answer 2

The best way to approach this question is that you know that the entire system must be equal to zero. Well that means either (t+3)=0, or (t-6)=0, otherwise the entire thing can't be equal to 0.
Well then you can solve the two individually, meaning t=-3 or t=6.

Answer 3

Are you solving the equation for t? If so then the answer is t= -3,6