A: Firstly to add fractions the denominators have to be the same.
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