Х + 1/20=3/4 - 1/5
х = 3/4 - 1/5 - 1/20
х = 15/20 - 4/20 - 1/20
х = 10/20
х = 1/2
3/8-t=1/20+1/5
3/8-t = 1/20+4/50
3/8 - t = 5/20
3/8 - t=1/4
t=3/8-1/4
t=3/8-2/8
t=1/8
16
6ц5/27 - 3ц7/18 = 6ц10/54 - 3ц21/54 = 5ц64/54 - 3ц21/54 = 2ц43/54 - разница между А и В
3ц7/18 - 2ц43/54 = 3ц21/54 - 2ц43/54 = 2ц75/54 - 2ц43/54 = 32/54 = 16/27
ответ С - 16/27