DariosI

Verified answer

2)5y+7y≤3-9
12y≤-6
y≤-6:12
y≤-1/2
y∈(-∞; -1/2]

3) 3a-2/5<a+7.6
3a-0.4<a+7.6
3a-a<7.6+0.4
2a<8
a<8:2
a<4
a∈(-∞; 4)
4) 2x-2-3x-6<6+6x
-x-8<6+6x
6x+x>-8-6
7x>-14
x>-14:7
x>-2
x∈(-2; +∞)
5) 8y-6y+9=2y+9
6) 7x-12=(x+13-5)*3
7x-12=(x+8)*3
7x-12=3x+24
7x-3x=24+12
3x=36
x=36:3
x=12