A ladder 13 m long is leaning against a wall. The bottom of the ladder is pulled along the ground away from the wall at the rate of 4 m/sec. Find the rate of decreasing at which the top of the ladder moving downwards on wall when the foot of the ladder is 5 m away from the wall.

Explanation

To solve the problem step by step, we will use the Pythagorean theorem and related rates.

### Step 1: Understand the Problem
We have a ladder of length 13 meters leaning against a wall. The bottom of the ladder is being pulled away from the wall at a rate of 4 m/sec. We need to find the rate at which the top of the ladder is moving down the wall when the bottom of the ladder is 5 meters away from the wall.

### Step 2: Set Up the Variables
Let:
- \( x \) = distance from the wall to the bottom of the ladder (in meters)
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