If Tomorrow is Sunday, what will be the day after 20 days

How do we solve it ?

If tomorrow is sunday, today is saturday.

A week has 7 days " Sunday, Monday, Tuesday, Wednesday, Thursday, Friday, Saturday ".

20 / 7 = 2 ( Remainder = 6)

So you can say that after multiples of 7 days, the day will repeat itself as saturday.

Hence after 14 days saturday will occur again.

So we calculate after the remainder (6) , the answer is Friday.

Simple Logic = And whatever the remainder obtained is, add that to the day.