A man has taken total 90 Coconuts

So he has 90 coconuts with 3 bags, he need to pay 3 coconuts till he has 3 bags

For first 10 booth, he will pay 30 coconuts, 3 coconuts per booth.

Coconuts pay = 10*3 ==> 30

Coconuts left = 90-30 ==> 60

Booth Left = 30-10 ==> 20

Now, he has 60 coconuts with 2 bags and 20 booth left. So he will pay 2 coconuts to the booth till he has 2 bags

For next 15 booth, he will pay 30 coconuts

Coconuts pay = 15*2 ==> 30

Coconuts left = 60-30 ==> 30

Booth Left = 20-15 ==> 5

Now, he has 30 coconuts with 1 bag and 5 booth left. So he will pay 1 coconuts to the booth

Coconuts pay = 5*1 ==> 5

Coconuts left = 30-5 ==> 25

Booth Left = 5-5 ==> 0

So coconuts left is 25

Ans :- Maximum coconuts a man can take home = 25