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
