Given a list of numbers, find all pairs of numbers whose difference is equal to a given target number.
List: {7, 4, 2, 1, 9, 8}
Target number: 4
Here are the pairs of numbers in the list {7, 4, 2, 1, 9, 8} whose difference is equal to the target number 4:

- (7, 1)
- (9, 5)

Note: The order of the pairs does not matter, and the order of the numbers within each pair does not matter.
Complete the following task based on the instruction and optional input provided.### Instruction:
Given a list of numbers, find all pairs of numbers whose difference is equal to a given target number.

### Input:
List: {7, 4, 2, 1, 9, 8}
Target number: 4

### Output:
Here are the pairs of numbers in the list {7, 4, 2, 1, 9, 8} whose difference is equal to the target number 4:

- (7, 1)
- (9, 5)

Note: The order of the pairs does not matter, and the order of the numbers within each pair does not matter.