So. To explain in a smaller picture,
If you have 1 apple, you would need 3 oranges.
To find how many oranges you need : multiply the amounts of apples you have by 3.
If your fruit salad uses 4 apples, then you would need 12 oranges .. why?
Because 4 x 3 is 12.
Hope this helps! Please mark brainliest.