To find the median:

1. Arrange the numbers in ascending or descending order.
2. If the dataset has an odd number of values, the median is the middle number.
3. If the dataset has an even number of values, the median is the average of the two middle numbers.

Let's calculate the median of the following set of numbers: 10, 15, 20, 25, 30.

1. Arrange the numbers in ascending order: 10, 15, 20, 25, 30.
2. Since the dataset has an odd number of values, the median is the middle number, which is 20.

So, the median of the set {10, 15, 20, 25, 30} is 20. Now, let's calculate the median of another set of numbers: 5, 10, 15, 20, 25, 30.

1. Arrange the numbers in ascending order: 5, 10, 15, 20, 25, 30.
2. Since the dataset has an even number of values, the median is the average of the two middle numbers, which are 15 and 20.
3. Calculate the average: (15 + 20) / 2 = 35 / 2 = 17.5.

So, the median of the set {5, 10, 15, 20, 25, 30} is 17.5.