DHAcity 3)
1/6x + 5/12x=8.4/10=8.2/5=42/5

2/12x+ 5/12x=42/5

7/12x=42/5

x=42/5:7/12=42/5 

х 12/7=6/5 

х 12=72/5

x=14.2/5 

Ежели

x=14,4

4)

3/9y+5/9y=8/9y

8/9y=72/10

y=72/10 : 8/9
y=72/10*9/8
y=81/10
y=8,1

5)
1,2(3b+5)=2(2,4b-3,6)
3,6b+6=4,8b-7,2
3,6b-4,8b=-7,2-6
-1,2b=-13,2
b=-13,2/(-1,2)
b=11

6)