Equation of straight line with slope 3 and passing through the point (30,40) is (y−40)=3(x−30)⇒y−40=3x−90⇒3x−y=50350​x​+−50y​=1.....(i) and equation of straight line with slope 6 and passing through the point (30,40) is (y−40)=6(x−30)⇒y−40=6x−180⇒6x−y=140⇒370​x​+−140y​=1......(ii) ∴ The difference between the y -intercepts of the straight lines