Final answer:
Melanie has 6 autographed baseballs.
Step-by-step explanation:
To find out how many autographed baseballs Melanie has, we can set up an equation. Let's say Melanie has x autographed baseballs. Since Diego has 4 times as many as Melanie, we can write the equation as 4x = 24. To solve for x, we divide both sides of the equation by 4, giving us x = 6. Therefore, Melanie has 6 autographed baseballs.