Explanation:
4a-4 =8+a
We can eliminate (-4) by (+4) using the inverse operation
4a-4+4=8+4+a
-ve 4 and +4 will be zero
4a=12+a
since 4a and a are like terms, bring a on the right side to the left side which becomes -a
4a-a = 12
3a = 12
now , bring 3 on the right side so we know the value of a
a = 12/3
a = 4