If a box contains 12 red balls and 4 green balls, what fraction of balls are red?

To determine the fraction of balls that are red, one must first find the total number of balls in the box. In this case, there are 12 red balls and 4 green balls, which sums up to 16 balls in total (12 + 4 = 16).

Next, the fraction of red balls is calculated by taking the number of red balls (12) and dividing it by the total number of balls (16). This yields the fraction 12/16. To simplify this fraction, both the numerator and denominator can be divided by their greatest common divisor, which is 4.

Doing this simplification results in 12 ÷ 4 = 3 for the numerator and 16 ÷ 4 = 4 for the denominator, leading to a simplified fraction of 3/4. Thus, the final fraction representing the portion of red balls is 3/4.

This result corresponds to the correct answer, indicating that three-fourths of the balls in the box are red.