Add the fractions 2/5 + 3/7.

We must find a common denominator between the fractions to be able to add them (the bottom numbers must be the same). A common denominator of 5 and 7 is 35. To get to 35 from 5 we multiplied by 7, therefore we must multiply the 2 by 7 (whatever you do to the top you must do to the bottom). Our new fraction is 14/35. To get to 35 from 7 we multiplied by 5, therefore we must multiply the 3 by 5. Our second new fraction is 15/35. Now that we have common denominators, we can add the top fractions. 14/35 + 15/35 = 29/35. The fraction cannot be simplified. 29/35 is our answer.