(4z)/(8z)-(2m)/(m)+(6m)/(5m)+(5z)/(7z)

[latex] \frac{4z}{8z}- \frac{2m}{m}+ \frac{6m}{5m}+ \frac{5z}{7z}= \frac{1}{2}- \frac{2}{1} + \frac{6}{5}+ \frac{5}{7}= \frac{1*35-2*70+6*14+5*10}{70} = \\ \\ = \frac{35-140+84+50}{70} = \frac{29}{70} [/latex]