While finding the refractive index of a glass slab, the travelling microscope is focused on ink dot on a white paper at position 4.320cm. When a glass slab is placed on this ink dot on paper, the microscope is raised through 1.80cm. The thickness of glass slab of refractive index $\frac{3}{2}$ is x then find the value of $\frac{5x}{27}$ :