In the following question, select the related number from the given alternatives.
9 : 50 :: 20 : ?

Given: 9 : 50 :: 20 : ?

Logic: (1st number $$\times$$ 5) + 5 = 2nd number

For, 9 : 50

9 $$\times$$​ 5 = 45, 45 + 5 = 50

Similarly,

20 : ?

20 $$\times$$​ 5 = 100, 100 + 5 = 105

Thus, correct option is (a).