In the following number-pairs, the second number is obtained by applying certain mathematical operations to the first number. Which numbers should replace X and Y so that the pattern followed by the two numbers on the left side of :: is same as that on the right side of :: ?

(NOTE: Operations should be performed on the whole numbers, without breaking down the numbers into its constituent digits. E.g. 13 - Operations on 13 such as adding/subtracting /multiplying etc. to 13 can be performed. Breaking down 13 into 1 and 3 and then performing mathematical operations on 1 and 3 is not allowed)

X : 120 :: 4 : Y

​X : 120 ::4 :Y 

​6³− 6 = 216 − 6 = 210 $$\not=$$​ 120

​Option A does not work.​

5³− 5 = 125 − 5 = 120

4³− 4 = 64 − 4 = 60 (Follow)

9³− 9 = 729 − 9 = 720 $$\not=$$120 (Not follow)

5³− 5 = 125 − 5 = 120

​4³− 4 = 64 − 4 = 60 $$\not=$$ 70 (Not follow)

So, option B X = 5, Y = 60 is follow.

Thus, the correct option is: (b)