[ \frac{3}{a} - \frac{4}{a+1} ][ \frac{a-1}{a} \cdot \frac{a}{a-1} = 1 ][ \frac{a+1}{a} \quad \text{or} \quad \frac{a-1}{a+1} ]
[ \frac{3}{a} - \frac{4}{a+1} ]
[ \frac{a-1}{a} \cdot \frac{a}{a-1} = 1 ]
[ \frac{a+1}{a} \quad \text{or} \quad \frac{a-1}{a+1} ]