The answer is 9/15 because you have to multiply the denominator of 1/3 by 5 to have the same denominator of 4/15. After you do that also multiply the numerator of 1/3 by 5 as well, your new fraction should be 5/15 after now have both fractions with the same denominator, you add the two numerators, don't have to add the denominators and should get 9/15. Hope this helped.
