A delivery man has to deliver packets to four houses which are numbered as on a number line. He has packets for house numbers 9, -8, -3 and -12. If he has delivered the packet at house no. 9, write the order in which he should deliver the packets to minimise his walk.

Answer

To solve the problem of determining the order in which the delivery man should deliver packets to minimize his walk, we can follow these steps:

### Step 1: Identify the positions of the houses on a number line.
The houses are located at the following positions:
- House 1: 9 (positive side)
- House 2: -8 (negative side)
- House 3: -3 (negative side)
- House 4: -12 (negative side)

### Step 2: Plot the positions on a number line.
On a number line, we can visualize the positions as follows:

```
... -12 -11 -10 -9 -8 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 6 7 8 9 10 11 12 ...
| | | |
-12 -8 -3 9
```

### Step 3: Determine the starting point.
The delivery man starts at house number 9 after delivering the packet there.

### Step 4: Plan the route to minimize walking distance.
To minimize the walk, the delivery man should move towards the left (negative side) since he starts at 9. The order of delivery should be from the house closest to 9 to the farthest on the left.

### Step 5: List the houses in order of delivery.
1. First, he should deliver to house -3 (closest to 9).
2. Next, he should deliver to house -8.
3. Finally, he should deliver to house -12 (farthest from 9).

### Final Order of Delivery:
- Deliver to house -3
- Deliver to house -8
- Deliver to house -12

This order minimizes the distance the delivery man has to walk.

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