3.1. Решить уравнение: 15 3/8:(2 3/4x+5 5/6)−1 1/2=3/4.

\(15\frac38:(2\frac34x+5\frac56)=\frac34+1\frac12=\frac94\).

\(15\frac38=\frac{123}{8}\), поэтому

\(2\frac34x+5\frac56=\frac{123}{8}:\frac94=\frac{123}{8}\cdot\frac49=\frac{41}{6}\).

\(\frac{11}{4}x+\frac{35}{6}=\frac{41}{6}\).

\(\frac{11}{4}x=1\), \(x=\frac4{11}\).

Ответ: \(x=\frac4{11}\).