[tex]6x^2+66x+60\\6(x^2+11x+10)\\6(x+1)(x+10)[/tex]
Common Factor 6 out of the terms as you should get 6(x²+11x+10) then factor inside and you get (x+1)(x+10) because
x*x = x² (first)
[x(10)]+[1(x)] = 10x+x = 11x (middle)
10*1 = 10 (last)
So the answer is 6(x+1)(x+10)