Вариант 19.3. Выполни указанные действия: 1) 2 2/5 : 1 3/10; 2) 1 13/21 + 4/9; 3) 4/5 : 3 1/2; 4) 3 · 4 1/3; 5) 4 5/6 − 3 5/8; 6) 1 2/19 · 1 2/7; 7) 1 8/21 + 3 2/7; 8) 2 − 1 12/19.

1. \(2\frac25:1\frac3{10}=\frac{12}{5}:\frac{13}{10}=\frac{12}{5}\cdot\frac{10}{13}=\frac{24}{13}=1\frac{11}{13}\).
2. \(1\frac{13}{21}+\frac49=\frac{34}{21}+\frac49=\frac{102+28}{63}=\frac{130}{63}=2\frac4{63}\).
3. \(\frac45:3\frac12=\frac45:\frac72=\frac45\cdot\frac27=\frac8{35}\).
4. \(3\cdot4\frac13=3\cdot\frac{13}{3}=13\).
5. \(4\frac56-3\frac58=\frac{29}{6}-\frac{29}{8}=\frac{116-87}{24}=\frac{29}{24}=1\frac5{24}\).
6. \(1\frac2{19}\cdot1\frac27=\frac{21}{19}\cdot\frac97=\frac{27}{19}=1\frac8{19}\).
7. \(1\frac8{21}+3\frac27=\frac{29}{21}+\frac{23}{7}=\frac{29+69}{21}=\frac{98}{21}=\frac{14}{3}=4\frac23\).
8. \(2-1\frac{12}{19}=\frac{38}{19}-\frac{31}{19}=\frac7{19}\).

Ответ: 1) 1 11/13; 2) 2 4/63; 3) 8/35; 4) 13; 5) 1 5/24; 6) 1 8/19; 7) 4 2/3; 8) 7/19.