TeX source:
\frac{\qquad a+\frac{a}{b}\qquad}{\qquad 1+\frac{1}{b}\qquad}=\frac{\qquad\frac{ab+a}{b}\qquad}{\qquad\frac{b+1}{b}\qquad}=\frac{(ab+a)}{b}\cdot \frac{b}{(b+1)}=\frac{(ab+a)b}{b(b+1)}= \frac{a (b+1) b}{b (b+1)}= a