Final answer:
To find the missing numerator, determine the least common multiple of the denominators 6 and 15, which is 30. Convert each fraction to have this common denominator and then add the numerators, resulting in the missing numerator being 26.
Step-by-step explanation:
To find the missing numerator for the sum of the fractions 4/6 and 3/15, we must first obtain a common denominator. We can do this by finding the least common multiple (LCM) of the two denominators, which is 30 in this case. We then convert each fraction to have this common denominator by multiplying the numerator and denominator of each fraction by the necessary factor.
For the first fraction, 4/6, we multiply by 5/5 to get 20/30. For the second fraction, 3/15, we multiply by 2/2 to get 6/30. Now we can add the numerators since the denominators are the same: 20/30 + 6/30 equals 26/30. Therefore, the missing numerator when these fractions are added and have the same denominator is 26.