a)3+x=6
3+x-3=6-3
x=6-3
x=3
b)3x=6
3x:3=6:3
x=6:3
x=2
[tex]c) \frac{x}{6} = \frac{2}{3} \\ \\ \frac{3x}{6} = 2 \\ \\ 3x = 2 \times 6 \\ \\ 3x = 12 \\ \\ 3x : 3 = 12 : 3 \\ \\ x = 12 : 3 \\ \\ x = 4[/tex]
d)4x+5=3x+6
4x-3x+5=3x-3x+6
4x-3x+5=6
4x-3x+5-5=6-5
4x-3x=6-5
(4-3)x=6-5
1x=6-5
x=6-5
x=1