Three fourths of the offspring of two fruit flies have short wings, while the rest have wild-type wings . In a batch of offspring from those two flies, 100 have wild-type wings. How many of the flies have short wings?

300

Step-by-step explanation:

If three-fourths of the offspring of two fruit flies have short wings and the rest have wild-type wings, then of the offspring must have wild-type wings. This means that the number of offspring that have short wings must be times larger than the number of offspring that have wild-type wings. Since there are 100 offspring who have wild-type wings, there must be that have short wings.

Alternative:

If three-fourths of the offspring of two fruit flies have short wings and the rest have wild-type wings, then of the offspring must have wild-type wings. Therefore, 100 represents one-fourth of the total number of offspring, meaning there must be offspring total. Thus, there are offspring with short wings.