Help Reducing simple fraction

Question

This has got to be easy, but for some reason I just don't see it, probably because it's late.

Solution key to a quiz we took online says that:

$\frac{A^2 + A + AB}{(A + B)(A + B + 1)}$

can get reduced down to

$\frac{A}{A+B}$

but I can't seem to get it there. Any help?

Answer 1

Hint: Use $A^2+A+AB=A(A+1+B)$.

Answer 2

This is because $A^2+A+AB=A(A+B+1)$.