Algebra 1 problems

I have some sample algebra 1 problems below. This is continuous of my previous post where i had solved a few simple algebra problems. Now look at the below mentioned example friends!!

Example 1:

solve 9-x = -12

Solution:

9-x = -12

Add 12 on both sides.

9-x+12=-12+12

21-x=0

Add x on both sides,

21-x+x=x

21=x

x=21

Here you see some steps also in this above mentioned problem. Look at my post on point slope formula, a very useful post guys.