Решите пропорции: а) x : 12 = 4 3/4 : 7 1/5; б) 6 1/2 : x = 6 5/6 : 4,1; в) 3 1/3 · x : 1,5 = 4 2/7 : 3/14; г) 3 7/19 : 1 1/2 = 2 3/8 : 0,8x.

1. \(x:12=4\frac{3}{4}:7\frac{1}{5}\).

   \(x=12\cdot\frac{4\frac{3}{4}}{7\frac{1}{5}}=12\cdot\frac{19}{4}\cdot\frac{5}{36}=\frac{95}{12}=7\frac{11}{12}\).

2. \(6\frac{1}{2}:x=6\frac{5}{6}:4.1\).

   \(x=\frac{6\frac{1}{2}\cdot4.1}{6\frac{5}{6}}=\frac{13}{2}\cdot\frac{41}{10}\cdot\frac{6}{41}=\frac{39}{10}=3.9\).

3. \(3\frac{1}{3}\cdot x:1.5=4\frac{2}{7}:\frac{3}{14}\).

   \(\frac{10}{3}x\cdot\frac{2}{3}=\frac{30}{7}\), поэтому \(x=\frac{30}{7}\cdot\frac{9}{20}=\frac{27}{14}=1\frac{13}{14}\).

4. \(3\frac{7}{19}:1\frac{1}{2}=2\frac{3}{8}:0.8x\).

   \(\frac{64}{19}\cdot\frac{2}{3}=\frac{19}{8}\cdot\frac{1}{0.8x}\), откуда \(0.8x=\frac{19}{8}\cdot\frac{57}{128}=\frac{1083}{1024}\), \(x=\frac{1083}{1024}\cdot\frac{5}{4}=\frac{5415}{4096}\).

Ответ: а) \(7\frac{11}{12}\); б) \(3.9\); в) \(1\frac{13}{14}\); г) \(\frac{5415}{4096}\).