how to find the pressure at a depth of a fluid of variable density?explain with a problem?

Let P be pressure and ρ be density(varies with position). dP = ρg.dy, where g is the acceleration due to gravity and dy is the infinitesimal change in position within the fluid.  Thus, P2 - P1 = ∫ρg.dy , where y1 and y2 are the lower and upper limits of integration respectively. This is a universal relation implying that it can be used in any situation.