Using the chain rule, we know that dy/dx = dy/dt . dt/dx Therefore we differentiate both equations with respect to t:dx/dt = -4dy/dt = -2/(t^2)therefore dy/dx = -1/4 . -2/(t^2)dy/dx = 1/(2t^2) ... (we know that t = (3-x)/4 )therefore dy/dx = 8/((3-x)^2)