Divide 72kg in the ratio of 1 3 5

First add the ratio 1:3:5 together to give you the total number:
             1 + 3 + 5 + = 9
Therefore you divide 72 by 9 to give you one part 
             72 divide 9 = 8 
Now you times each part of the ratio by 8:
             1 x 8 = 8 
             3 x 8 = 24 
             5 x 8 = 40 
Therefore the answer would be written like this:
8:24:40 

Hope this helps