First step to solving a two step algebraic is to find the variable. 

5 + 4n = 29

So as you can see on in the top example i have just high light the variable. Now that you'v found your variable, the next step is to go and isolate the variable to find out what the letter means.

5 + 4n - 5 = 29 - 5  

        4n = 24

Now that you've isolated the variable, next what you're trying to do is getting rid of the number right beside the variable, how do you do that you may ask? You are going to get the reciprocal (or the opposite of the number) in this case it is 4n, the reciprocal is 1/4, so you'll divide it on both sides of the equation.

4n = 24

4       4

n = 6

As you can see after we have divided 4n over 4 along with dividing 24 over four we end up with the 4 being eliminated thus leaving us left with n =, and 24 over 4 leaves us with 6. The variable means or is 6. don't forget to verify or check your answer!

5 + 4n = 29 

5 + 4(6) = 29

29 = 29