ELI5. This math problem


I saw this on discord and I feel like an idiot but I’m so confused.

*”Question for you guys If I borrow $50 from my mom and $50 from my dad to purchase an object worth $97. Since I would have $3 change I would give one to my mom and one to my dad and keep one my self
So I still owe my mom $49 and my dad $49 that means I owe $98 counting the one I have makes is $99 where did the other $1 go?”*

In: Mathematics

IIRC, the logic error is that you’re changing from tracking the money to tracking what you owe and then mixing up the different terms into one calculation, which aren’t the same thing. I don’t recall the technical jargon.

I do remember how to solve it: count the *dollars alone* from the end backward. Mom has a dollar, Dad has a dollar, I have a dollar. The other $97 are at the store.

The dollar didn’t “go” anywhere. The next to last Line incorrectly says you “have” 99 dollars. You don’t have 99 dollars, you have 1 dollar. You owe 98 dollars still.

Consider thst if you split the 3rd dollar into 50 cents, then you would only owe 97 and it would be equal across parents.

It’s a misdirection. You do owe $98 total, having paid $2 back. That third dollar you kept, you down’t owe yourself.

“Counting the one i have” doesn’t make any sense for the problem. It doesn’t make sense to count the $1 he has as something he/she owes their parents. And the $100 value is also completely irrelevant so the “other dollar” doesn’t matter

In short, this is nonsense 🙂

You owe $98 total. And you have $98 worth of stuff ($97 object plus $1). 98 including the one you have is just 98, not 99.