The answer is 125 oranges. You can find this by first writing the ratio of oranges to apples as 5:3. Then, we know that the apples side must be 75, so we need to find out how much to multiply 3 by to get there, which we can do by dividing 75 by 3 to get 25. This means we can multiply 5 by 25 aswell to get the ratio as 125:75, so there are 125 oranges.
I hope this helps!