Form the lens formula = \(\frac{1}{\text{U}}\) + \(\frac{1}{\text{V}}\) = \(\frac{1}{\text{f}}\) => \(\frac{1}{10} + \frac{1}{25}\) = \(\frac{1}{\text{f}}\) ∴ \(\frac{(5 + 2)}{50}\) = \(\frac{1}{\text{f}}\) ∴ f = \(\frac{50}{7}\)cm Since the image is observed on a screen, it is a real image. Thus magnification M =\(\frac{\text{f}}{U - f}\) = \(\frac{\frac{50}{7}}{10 - \frac{50}{7}}\) ∴ M = \(\frac{\frac{50}{7}}{\frac{20}{7}}\) = \(\frac{50}{7}\) x \(\frac{7}{20}\) = 2.5 Or m = \(\frac{\text{v}}{\text{u}}\) = \(\frac{25}{10}\) = 2.5