Ethan, chris and jon have $90 altogether. ethan has a half of that amount and chris has one third of all the money. how much does jon have?

The answer would be 15.

If Ethan has half of $90. You would have to divide $90 by 2, giving you $45.

And if Chris has a third of $90. You would have to divide $90 by 3, giving you $30.

Now, Chris. That leaves Chris with the rest of the money missing that adds up too $90. So if, $45 plus $30 equals $75. Subtract $75 from $90 which gives you $15 left.

Hope I helped!!