Вычислить: а) 8/9*3/4 - (5/6-1/4) б) 3/5+4/5*3/7+6/7 в) (2/5-2/7) : 2/7*2/5 г) (5/6-3/10) : (3/10+2/15)

а) 8/9*3/4 - (5/6-1/4) = 2/3*1 - (10/12-3/12) = 2/3 - 7/12 = 8/12 - 7/12 = 1/12.

б) 3/5+4/5*3/7+6/7 = 3/5+12/35+6/7 = 21/35+12/35+30/35 = 63/35 = 1.28/35.

в) (2/5-2/7) : 2/7*2/5 = (14/35-10/35) : 4/35 = 4/35 : 4/35 = 1.

г) (5/6-3/10) : (3/10+2/15) = (25/30-9/30) : (9/30+4/30) = 16/30 : 13/30 = 16/30*30/13 = 16/13 = 1.3/13