How to add fractions

For example, 3/7 + 2/3

firstly you need to work out the lcm of 7 and 3, in this case it is 21.

So each fraction needs to be put into the form a/21 + b/21

For the fraction 3/7, you are timsing the 7 by 3  to get 21, so you also need to times the numerator by 3 leaving you with 9/21 which = 3/7 

Then starting with 2/3, to get a denominator of 21, you need to times 3 by 7, so you also need to times the numerator by 7 leaving you with 14/21 which =2/3

Finally to add the 2 fractions 9/21 + 14/21 = 23/21

Other examples for you to try..

1) 3/5 + 2/3

2) 3/5 + 6/20