Problem above. I see it's based on the LORAN long range navigation system, but my book was very nondescript about it, except that the boat is located where the branches of 2 hyperbolas meet(see 2nd pic). With the given information I am hard pressed to find any equation(I thought there were 2 equations!) because the boat is not equidistant from the transmitters. Trying to find such distances with the difference in signal transmisseon gives me s=x+37.2 and t=x, but thats about as far as I get without running out of numbers.