To add any given fraction you must have a common denominator! (Remember that the top is the numerator, and the bottom is the denominator!) So, if you have an expression like this:
1/2 + 2/3 = ?
You need to find what is the smallest number that both 2 and 3 have in common. In this case it is 6. (Because 2*3 = 6, and 3*2 = 6)
(1/2)*(3/3) + (2/3)*(2/2)
Multiply across. (So the numerators multiply, and then the denominators multiply)
