1) преобразуем дроби с целыми числами в правильные дроби:
32/3 : 8/9 - 6.8 = 32/3 *9/8 - 6.8 = 288/24 - 6.8 = 12-6.8 = 5.2
2)также преобразуем:
16/3 :20/9 + 0.6 = 16/3 * 9/20 + 0.6 = 144/60 + 0.6 = 2.4+0.6 = 3
3) (2.25+ 11/6)*6/7 -0.5 = (225/100+11/6)*6/7 -0.5= ((675+550)/300)*6/7 -0.5=
=1225/300*6/7 -0.5 = 1225/350 -0.5= 3.5-0.5= 3
4) (9.2-15/4):2.5+0.82= (92/10 - 15/4):2.5+0.82=(184-75)/20 :2.5+0.82=
=109/20 :2.5+0.82 = 109/20 : 25/10 + 0.82=109/20 *10/25 + 0.82= 1090/500 +0.82 = 2.18+0.82= 3