Solution:
School closes for the summer vacation on 31st March 2022 (31/03/2022) [ 0.5 marks ]
It reopens after 50 days (30+20 days)
We know that April has 30 days; 30 days after 31 st march 2022 will be on 30/04/2022. [ 0.5 marks ]
Now we need to add 20 days 30/04/2022,
20 days after 30/04/2022 will be on 20/05/2022. [ 1 mark ]