To add these together you must get the same denominator which in this case you want 6. So you multiply the bottom by 2. And whatever you do to the bottom of the fraction you have to do the top which means you have to multiply the 2 by 2 aswell. and when you add them together it should look like this.
to clarify the reason i multiplied by to was to get the denominator to be the same. which is needed to be able to add them together. and i meant to say 2/2 but i just wrote 2. (woops)
2/3X2=4/6 +1/6 = 5/6
hope I helped.
