(2 целых5/7)в кубе * 14/19
1) (2 целых 5/7)³ = (19/7)³ = 19/7 · 19/7 · 19/7 = 6859/343
2) 6859/343 · 14/19 = (361·2)/(49·1) = 722/49 = 14 целых 36/49