a) [tex]\frac{x+1}{3} = 7[/tex] /*3
x + 1 = 21
x = 21 - 1
x = 20
b) [tex]\frac{3-x}{2} = \frac{1}{3}[/tex]
3(3-x) = 2
9 - 3x = 2
-3x = 2 - 9
-3x = -7
x = [tex]\frac{7}{3}[/tex]
x = [tex]2\frac{1}{3}[/tex]
c) [tex]1 - 3x = \frac{1}{2}[/tex]
-3x = [tex]\frac{1}{2} - 1[/tex]
-3x = [tex]-\frac{1}{2}[/tex] /:(-3)
x = [tex]\frac{1}{6}[/tex]
d) [tex]\frac{1}{2}x + 1 = 4[/tex] /*2
x + 2 = 8
x = 8 - 2
x = 6
