1-\frac{3}{5}
3-\frac{4}{7}
12-5\frac{6}{11}
1-\frac{3}{5}=\frac{5}{5}-\frac{3}{5}=\frac{2}{5}
3-\frac{4}{7}=2\frac{7}{7}-\frac{4}{7}=2\frac{3}{7}
12-5\frac{6}{11}=6\frac{5}{11}