Найдите значение выражения 7/10 : (3/8 - 1/5).

Привет! Давай решим примеры с дробями по порядку. 2. $7/10 : (3/8 - 1/5) = 7/10 : (15/40 - 8/40) = 7/10 : 7/40 = 7/10 \cdot 40/7 = 4$ 3. $13/9 \cdot 8/7 + 22/63 = 104/63 + 22/63 = 126/63 = 2$ 4. $(1 \frac{3}{5} + 2 \frac{2}{15}) \cdot 9/56 = (1 \frac{9}{15} + 2 \frac{2}{15}) \cdot 9/56 = 3 \frac{11}{15} \cdot 9/56 = 56/15 \cdot 9/56 = 9/15 = 3/5 = 0,6$ 5. $17/9 : (2/9 + 1/4) = 17/9 : (8/36 + 9/36) = 17/9 : 17/36 = 17/9 \cdot 36/17 = 4$ 6. $1 \frac{1}{2} \cdot 5/12 : 1/4 = 3/2 \cdot 5/12 \cdot 4 = 15/24 \cdot 4 = 60/24 = 2,5$ 7. $2 \frac{1}{3} \cdot 9/16 : 3 \frac{1}{2} = 7/3 \cdot 9/16 : 7/2 = 7/3 \cdot 9/16 \cdot 2/7 = 3/8 \cdot 2 = 6/8 = 3/4 = 0,75$ 8. $1 \frac{2}{3} : 14/25 : 1/6 = 5/3 \cdot 25/14 \cdot 6 = (5 \cdot 25 \cdot 6) / (3 \cdot 14) = 750 / 42 = 125/7 = 17 \frac{6}{7}$ 9. $7/10 : (3/8 - 1/5) = 7/10 : (15/40 - 8/40) = 7/10 : 7/40 = 7/10 \cdot 40/7 = 4$ 10. $19/4 : (1/4 + 3/7) = 19/4 : (7/28 + 12/28) = 19/4 : 19/28 = 19/4 \cdot 28/19 = 28/4 = 7$ 11. $1 \frac{1}{3} : (5/6 - 3 \frac{1}{2}) = 4/3 : (5/6 - 7/2) = 4/3 : (5/6 - 21/6) = 4/3 : (-16/6) = 4/3 : (-8/3) = 4/3 \cdot (-3/8) = -4/8 = -1/2 = -0,5$ 12. $5/9 : (7/13 - 1/9) = 5/9 : (63/117 - 13/117) = 5/9 : 50/117 = 5/9 \cdot 117/50 = 13/10 = 1,3$