In order to add, subtract, or divide fractions, you must have a common denominator. A common denominator can be found by finding equivalent fractions. You can find a common denominator when you multiply, but it is not required.

The top number of a fraction is called the numerator.
The bottom number of a fraction is called the denominator.
Example: 1/3
1 is the numerator and 3 is the denominator.

Fractions are division problems. 1/3 can be read as one-third or one divided by three.
Many times you can solve a problem, simply by reducing.
For example, let's say I do a problem and end up with 24/18. This reads as 24 divided by 18. Of course, I can make the division box and proceed to complete the problem, but I can reduce that by dividing out a factor of 6.
24/18 is equivalent to 4/3. This now reads as 4 divided by 3. 3 goes into 4 one time with a remainder of 1, so my answer would be 1 and 1/3 or approximately 1.33

Equivalent Fractions:
Fractions are equivalent if they are equal to each other.
1/2 = 4/8
I know these fractions are equivalent because they have the same scale factor. I would multiply the numerator and denominator by 4 in order to get my new numerator and denominator.