2 Answers

2s + 8  < 20
2s + 8 - 8 < 20 - 8  (Getting the unknown all by itself on one side of the < sign;  What you do on one side of the equation you must do on the other side to keep it "in balance"; subtract 8 on both sides)

2s < 12

2s/s < 12/2  (Dividing the 2s by 2 will give you 's' all by itself; again, what you do on one side you must do on the other...divide by 2)

s< 6
That's all for tonight.  You do some and post them.  I'll make sure they are OK. 
I'm assuming we are doing your homework, but maybe I'm wrong.

[Tips -Use the equal axiom to get the result]

Let us see the solution for this inequality

-2s + 8 < 20

i.e. 8-20 < 2s

i.e. -12 < 2s

i.e. -12/2 < s

So, -6 < s

Now solve the other related problems by yourself.