Question 21794
I will work your example for you, if you have futher questions you may ask.
Remember when working with fractions you must find the LCD (least common denominator)remember you are trying to get all the variables and numbers on different sides of the = sign.  I find it easier to explain it to begining students as if the numbers are one "team" and the variables are the other "team".  The teams oppose each other with the = sign being the middle man. each team must equal the other to be fair....understand?
ok your example was
3a + 1 = 2
______
  5        The first thing is to get rid of the 5 by multiplying both sides    
           by 5.  you do this because one side is a fraction which is actually
           indicating division by 5.
5 * 3a + 1
    ______
      5     = 2*5     this will get rid of your fraction, the 5s on the left
                      cancel each other out and you are left with

3a + 1 = 10           Move your "team" players to their correct side
3a=10-1               when you move the "team" players across the = sign they 
                      change from neg to pos or pos to neg.  understand?
3a=9                  here you still have a team member on the other side.  
                      since 3 is actually multiplying with the "a", you would 
                      divide each side by 3 to cancel out the 3 in front of the
                      "a"
3a = 9
--   --
3     3

a=3