Answer:
 Common fractions = 
 
 
Denominator = 6 
combination of fruits in basket having 30 fruits :

Combination of fruits in basket having 18 fruits :

Combination of fruits in basket having 24 fruits :

Combination of fruits in basket having 12 fruits :

Explanation:
Let x be fruits in any basket 
Since we are given that . In every basket, 1/2 of the pieces of fruit must be apples, 1/3 must be oranges, and 1/6 must be bananas.
Thus in basket having x fruits will have apples = 

And oranges = 

bananas = 

So, no matter how much fruits there in a basket the fraction of apples , oranges and bananas will remain same 
So, Common fractions = 
 
 
Denominator = 6 
Now combination of fruits in basket having 30 fruits :
Since we are given that 1/2 of the pieces of fruit must be apples, 1/3 must be oranges, and 1/6 must be bananas.

Now combination of fruits in basket having 18 fruits :
Since we are given that 1/2 of the pieces of fruit must be apples, 1/3 must be oranges, and 1/6 must be bananas.

Now combination of fruits in basket having 24 fruits :
Since we are given that 1/2 of the pieces of fruit must be apples, 1/3 must be oranges, and 1/6 must be bananas.

Now combination of fruits in basket having 12 fruits :
Since we are given that 1/2 of the pieces of fruit must be apples, 1/3 must be oranges, and 1/6 must be bananas.
