An arbitrary scale has the ice point at `-20^(@)` and the steam point at `180^(@)`. When the thermometer reads `5^(@)`, then find the read of centigrade thermometer.

Explanation

To solve the problem, we need to convert the reading from the arbitrary scale to the centigrade (Celsius) scale. Here’s a step-by-step solution:

### Step 1: Identify the Ice and Steam Points
The ice point (0°C) corresponds to -20° on the arbitrary scale, and the steam point (100°C) corresponds to 180° on the arbitrary scale.

### Step 2: Write the Formula for Conversion
The relationship between the readings on the two scales can be expressed as:
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