Solving the inequality
15>m+8

The easiest and safe way to solve this is to use a numberline. Draw it and mark 15. Now, you are told that m+8 is smaller than 15, this means, there is some point m+8 which is to the left of 15.

http://p1cture.it/images/testsds.png

Can you see what I did, in the right part, you have m+8 < 15

Now, remove 8 from m. What number do you expect m to be above? This is where you have m < ?

When you got the? that is the answer. Can you post what you get? :)