In order to solve this question you have to calculate at first the whole area that should be painted for the two sheds and after that you’ll multiply that number by 3 because you need 3 coats and by 4 because it takes 4 minutes to paint 1 meter squared. After that, just add 20 min which are for the coffee break. The solution would be as follows.
area of 1st side(without the door) A1= 2x1=2 squared meters
area of 2nd side(with door) A2=2.5x1=2.5 squared meters
total area for 2 sides =2+2.5=4.5
but for 1 shed you have 4 sides, 2 of each then you have
4.5x2=9 squared meters per 1 shed
you have 2 sheds then 9x2=18 squared meters
each square meters needs 4 min then 18x4=72 min
you need 3 coats the, 72x3=216 min
finally, 216min+20 min=236 min which gives you 3 hrs and 56 mins
Thank you for your clear explanation