He would need to buy 11 sets as 406-278 is 128 then you divide that by 12 and get 10.6666 which rounds up to 11 because you can’t buy .66 of a set. So he would have to buy 11 sets of forks, hope this helps
Pressure and depth have a directly proportional relationship. This is due to the greater column of water that pushes down on an object submersed.. so the deeper the liquid level the higher the pressure of the liquid.