Verified answer

Ответ:

AB/BC = 4/3

Пошаговое объяснение:

AB/BC = x/(7-x) = (AB+CD)/(AB) * (AB)/(AB+CD) = 1 + CD/AB.

AB = (4/7)(AB + CD)

BC = (3/7)(AB + CD)

AB/BC = (4/7)/(3/7) = 4/3