formula to of how many apples in a basket with a ratio of 3 to 5 apples to oranges with a total of 40 apples and oranges

if i was to do this quetsion, i would add 3 and 5 as thats the total on average and i will get 8

i divide 40 by 8

i get 5

that means that i will have to multiple 3 and 5 by 5

i will get 15 and 25

since i know the 5 apples was multiplied by 5 to get 25 apples

there are 25 apples in the basket