Answer:
8 friends, 9 shells and 5 coins.
Step-by-step explanation:
For this question you will need to know how to factorise a number in prime numbers.
72/2 => 36/2 => 18/2 => 9/3 => 3
So 72 is 2*2*2*3*3 = 72
Then 40 = 2*2*2*5
Their common factors are 2*2*2 = 8
So there's only 8 friends at most to have whole numbers.
To see how many shells you only need to do 72/8 = 9
For the coins, 40/8 = 5