Hi, I have a couple word problems that I have to do for homework and I am stuck on one of them.

When you swim underwater, the pressure in your ears varies directly with the depth at which you swim. At 10 feet, the pressure is about 4.3 pounds per square in, (psi). Write the particular equation expressing pressure in terms of depth.

I think that the general equation is p = kx but I'm not sure how to relate that to the problem. I would appreciate any help. Thanks!