For these problems, it's best to use the FOIL method. FOIL stands for First, Outer, Inner and Last.
For example, in (x+5)(x+6), using FOIL, we start with the first terms of each ordered pair.
(x+5)(x+6)
x*x=x²
And then the outer two terms of each ordered pair
(x+5)(x+6)
x*6=6x
Then the Inner two terms of each ordered pair
(x+5)(x+6)
5*x=5x
And finally the last terms of each pair
(x+5)(x+6)
5*6=30
So when we add all of them together we get
x²+5x+6x+30
simply
x²+11x+30
Now that you know the method, i'll do a few more without writing down the explanations..... remember first,outer,inner,last....
(x+5)(x+2)
x²+2x+5x+10
x²+7x+10
(x+1)(x+6)
x²+6x+1x+6
x²+7x+6
(y+3)(y+5)
y²+5y+3y+15
y²+8y+15
(a+8)(a+9)
a²+9a+8a+72
a²+17a+72
