$ \begin{aligned} 60\%x-\frac12&=\frac78 \\ 解：0.6x&=\frac78+\frac48 \\ 0.6x&=\frac{11}{8} \\ x&=\frac{11}{8}×\frac53 \\ x&=\frac{55}{24} \\ \end{aligned}$
$ \begin{aligned} \frac{5}{9}：x&=\frac13：\frac14 \\ 解：\frac13x&=\frac{5}{9}×\frac14 \\ \frac13x&=\frac{5}{36} \\ x&=\frac{5}{12} \\ \end{aligned}$
$ \begin{aligned} 2.5×1.2+5x&=100 \\ 解：3+5x&=100 \\ 5x&=100-3 \\ 5x&=97 \\ x&=\frac{97}{5} \\ \end{aligned}$
