An object is placed at a distance of `20cm` from a equi-concave lens of focal length `30cm`, whose one surface is silvered. If the radius of curvature of the silvered surface is `60cm`, find the position and nature of the image.

Explanation

To solve the problem step by step, we will follow these instructions:

### Step 1: Understand the System
We have an equi-concave lens with a focal length of \( f = -30 \, \text{cm} \) (negative because it is a concave lens). One surface of the lens is silvered, effectively turning it into a mirror. The radius of curvature of the silvered surface is \( R = -60 \, \text{cm} \) (negative for concave mirrors).

### Step 2: Calculate the Effective Focal Length
When one surface of the lens is silvered, we need to find the effective focal length of the combination (lens + mirror). The formula for the effective focal length \( F \) when one surface is silvered is given by:

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