You can work it out by Fractions or by simple Rule of Three
But the way of Tweedle-dum is not the way of Tweedle-dee.
You can twist it, you can turn it, you can plait it till you drop,
But the way of Pilly-Winky's not the way of Winky-Pop!
"Her Majesty's Servants," The Jungle Book by Rudyard Kipling