Решите пример с дробями по действиям 5 5/7: 8/21+1 6/7: (43/56-11/24)

5 ⁵/₇ : ⁸/₂₁ + 1 ⁶/₇ : (⁴³/₅₆-¹¹/₂₄) = 21

1/ ⁴³/₅₆ - ¹¹/₂₄= ¹²⁹/₁₆₈ - ⁷⁷/₁₆₈ = ⁵²/₁₆₈ = ¹³/₄₂
2/ 1 ⁶/₇ : ¹³/₄₂ = ¹³/₇ × ⁴²/₁₃ = ¹³ˣ⁴²/₇ₓ₁₃ =  6
3/ 5 ⁵/₇ : ⁸/₂₁ = ⁴⁰/₇ × ²¹/₈ = ⁴⁰ˣ²¹/₇ₓ₈ = 15
4/ 15 + 6 = 21

43/56 - 11/24 = 129/168 - 77/168 = 52/168 = 13/42;
1 6/7 : 13/42 = 13/7 • 42/13 = 6;
5 5/7 : 8/21 = 40/7 • 21/8 = 15;
15 + 6 = 21