Пошаговое объяснение:
3 3/7*3 1/2:(1 1/11-27/55 ) = 20
1) 1 1/11 - 27/55 = 1 5/55 - 27/55 = 60/55 - 27/55 = 33/55 = 3/5
2) 3 3/7 * 3 1/2 = 24/7 * 7/2 = 12
3) 12 : 3/5 = 12 * 5/3 = 20
