the common denominator is the number on the bottom of the fraction. in this case it would be 4 (in 3/4) and 3 (in 2/3), you have to find a number which equals the same for both! so 3 and 4 both go into 12. 3 × 4 and 4 × 3, so you common denominator is 12! but, you also have to multiple the same number up on the top number. so 3 × 3 and 2 × 4. Then you Add! but only the top numbers! you can only add/subtract fractions that have the same common denominator! your answer will end up being the improper fraction of 17/12. if you have to turn it into a decimal or make it proper, then do so ^^
to find a common denominator, you have to find the number which both numbers equally go into! so no decimals. check the times tables!
