If you would like to divide 180 in the ratio of 4 : 5 : 9, you can do this using the following two steps:
First, add the numbers: 4 + 5 + 9 = 18
Second, divide and multiply: 4 / 18 * 180 = 40
5 / 18 * 180 = 50
9 / 18 * 180 = 90
The result you are looking for is 40 : 50 : 90.