Е. Вычислите: 4/5 : 20; 42 · 6/7; 2,4 : 3/8; 1 5/7 : 6/7; 2 1/4 · 4/9; 8/15 : 2/5; 5/7 · 1 2/5; 2 4/5 : 1 2/5; 3/4 · 2/9; 1 1/2 : 0,3; 6 : 2/3; 1 2/7 · 2 1/3; 7/8 : 1 5/16; 2 1/7 · 0,7; 3 3/7 · 1 1/6.

Смешанные числа преобразуем в неправильные дроби. При делении умножаем на обратную дробь.

1. \(\frac45:20=\frac45\cdot\frac1{20}=\frac1{25}\)
2. \(42\cdot\frac67=36\)
3. \(2{,}4:\frac38=\frac{12}{5}\cdot\frac83=\frac{32}{5}=6{,}4\)
4. \(1\frac57:\frac67=\frac{12}{7}\cdot\frac76=2\)
5. \(2\frac14\cdot\frac49=\frac94\cdot\frac49=1\)
6. \(\frac8{15}:\frac25=\frac8{15}\cdot\frac52=\frac43\)
7. \(\frac57\cdot1\frac25=\frac57\cdot\frac75=1\)
8. \(2\frac45:1\frac25=\frac{14}{5}:\frac75=2\)
9. \(\frac34\cdot\frac29=\frac16\)
10. \(1\frac12:0{,}3=\frac32:\frac3{10}=5\)
11. \(6:\frac23=6\cdot\frac32=9\)
12. \(1\frac27\cdot2\frac13=\frac97\cdot\frac73=3\)
13. \(\frac78:1\frac5{16}=\frac78:\frac{21}{16}=\frac23\)
14. \(2\frac17\cdot0{,}7=\frac{15}{7}\cdot\frac7{10}=\frac32\)
15. \(3\frac37\cdot1\frac16=\frac{24}{7}\cdot\frac76=4\)