Correct Answer - `-4cm ; -20cm`

Here, `h_(2) = - 10 mm, h_(1) = 2.5 mm, u = - 5 cm, f = ? , v = ?`

As `m = (h_(2))/(h_(1)) = -v/u, (-10)/(2.5) = (-v)/(-5) or v = -20 cm`

Negative sign of v shows that image is real.

`(1)/(f) = (1)/(v) + 1/u = 1/(-20) - 1/5 = (-1-4)/20 or f = (-20)/5 = -4 cm`.