1. Найдите значение выражения: 1) 7,59 + 4,8; 2) 19,4 − 13,54; 3) 9,04 · 5,7; 4) 4,56 : 5,7; 5) 3/8 + 2/7; 6) 9 7/16 − 4 3/20; 7) 15/19 · 26/21; 8) 2 1/2 : 1 2/3.

1. \(7.59+4.8=12.39\).
2. \(19.4-13.54=5.86\).
3. \(9.04\cdot5.7=51.528\).
4. \(4.56:5.7=0.8\).
5. \(\frac{3}{8}+\frac{2}{7}=\frac{21}{56}+\frac{16}{56}=\frac{37}{56}\).
6. \(9\frac{7}{16}-4\frac{3}{20}=5+\left(\frac{35}{80}-\frac{12}{80}\right)=5\frac{23}{80}\).
7. \(\frac{15}{19}\cdot\frac{26}{21}=\frac{390}{399}=\frac{130}{133}\).
8. \(2\frac{1}{2}:1\frac{2}{3}=\frac{5}{2}:\frac{5}{3}=\frac{5}{2}\cdot\frac{3}{5}=\frac{3}{2}=1\frac{1}{2}\).

Ответ: 1) 12,39; 2) 5,86; 3) 51,528; 4) 0,8; 5) 37/56; 6) 5 23/80; 7) 130/133; 8) 1 1/2.