What is the sum of 5/8+3/10

You first change the fractions so their denominators are the same:

5/8*5/5=25/40

3/10*4/4=12/40

Then you add the two sums up:

25/40+12/40=37/40

You just add the numerator. You don't have to add the denominators.

Change 5/8 and 3/10 so they have the same denominator

5/8*5/5=25/40

3/10*4/4=12/40

25/40+12/40=37/40

5/8+3/10=37/40