To add fractions with the same denominator, we can simply add the numerators together and keep them over the same denominator. This is modeled below:
3/8 + 2/8 = (3+2)/8 = 5/8
We know that 5/8 is in simplest form because the greatest common factor between the numerator and the denominator is 1.
Therefore, your answer is 5/8.
Hope this helps!