How to simplify derivatives 
The math problem asks to find the derivative of the function
  $$y=(x+1)^4(x+5)^2$$

I get to the part $$(x+1)^4 \cdot 2(x+5) + (x+5)^2 \cdot 4(x+1)^3$$
How do they arrive at the answer
$$2(x+1)^3(x+5)(3x+11) ?$$

$$(x+1)^4 \cdot 2(x+5) + (x+5)^2 \cdot 4(x+1)^3$$
$$(x+1)^3((x+1) \cdot 2(x+5) + (x+5)^2 \cdot 4)$$
$$(x+1)^3(x+5)( (x+1)\cdot 2 + (x+5) \cdot 4)$$
$$(x+1)^3(x+5)( 2)((x+1)+ (x+5)2)$$
$$2(x+1)^3(x+5)(x+1+2x+10)$$
$$2(x+1)^3(x+5)(3x + 11)$$
