Answer:
P =40.69 atm
Explanation:
We need to find the approximate pressure at a depth of 400 m.
It can be calculated as follows :
P = Patm + ρgh
Put all the values,

So, the approximate pressure is equal to 40.69 atm.
I believe its newtons 3rd law for every action there is an equal but opposite reaction since the squid is moving foward by shooting the water its pushing the squid back as its reaction. Hope this helped !