Correct Answer - `8//3 mm`, virtual at `v = -20`, no inversion
`(n_(2))/(v) - (n_(1))/(u) = (n_(2) - n_(1))/(R), (1)/(v) - (3)/(2xx(-15)) = (1-3//2)/(-10)`
`(1)/(v) + (1)/(10) = (-1)/(10) rARr v = -20cm` (virtual)
`- (n_(2))/(v^(2)) dv + (n_(1))/(u^(2)) du = 0, (1)/(400)dv = (3)/(2xx225) xx 1mm`
`dv = (400)/(2xx75)mm (8)/(3)mm`
`+ve,dv rArr "no inversion"`