Ответ:(1/4 + 3/4) + (3/5 + 3/5) = 1 + 6/5 = 2 1/5.(4/5 + 3/5) + (1/3 + 2/3) = 7/5 + 1 = 2 2/5.(2 4/7 + 4 3/7) + (1 2/9 + 3 4/11) = 7 + 4 58/99 = 11 58/99.