Igornatev А)2\3x+4\9x=3,2
6/9x+4/9x=3 1/5
10/9x=16/5
x=16/5×9/10
x=72/25
x=2 22/25

б)5\12x-4\15x=0,51
25/60x-16/60x=51/100
9/60x=51/100
x=51/100×20/3=17/5=3 2/5
проверка:
5/12×17/5-4/15×17/5=17/12-68/75=425/300-272/300=153/300=51/100=0,51

в)x-0,2x=8\15
0.8x=8/15
x=8/15×5/4
x=2/3