I'll solve one from each kind
Q1)
6 = a/4 + 2 (mutiply both sides)
24 = a + 8 (move the terms)
-a = 8 - 24 (calculate)
-a = 8 - 16 (change the signs)
a = 16
Q8)
2( 2 + 5) = -2 (divide both sides)
n + 5 = -1 (move the constant to the right)
n = -1 - 5 (calculate)
n= -6
Q3)
9x - 7 = 7 (cancel equal terms)
9x = 0 (divide both sides)
x = 0