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.