Find a common denominator
2/3+4/5
the CD is 15 because 3 and 5 both go into them.
find how many time the bottom part of the first fraction can go into there.
in this case, 3 can go into 15, 5 times
so then youll mutiple your top number by 5
repeat this for the next fraction
Once you have your four fractions, subtract the top of the two new fractions
in this case it'll be 10 and 12
=2
then put that over 15
=2/15