Question

Divide 72 kg in a ratio of 1:3:5

Answer 1

8:24:40 because 72/9 (3+1+5=9) which equals 8

Answer 2

If the 3 numbers are in the ratio of 1:3:5, then all together,
they make (1 + 3 + 5) = 9 parts.

Since 72 has been split up into 9 parts, each part is (72 / 9) = 8 .

So the numbers are

1 part . . . . 1 x 8 = 8
3 parts . . . 3 x 8 = 24
5 parts . . . 5 x 8 = 40

Check:

8 / 8 = 1
24/8 = 3
40/8 = 5

8 + 24 + 40 = 72 yay !

and a shout-out to Silversoul, who has so graciously
given me so many chances to fix my typos.