The Collatz conjecture is one of the most famous unsolved mathematical problems, because it's so simple, you can explain it to a primary-school-aged kid, and they'll probably be intrigued enough to try and find the answer for themselves.

Hi, you've asked an incomplete question. However, I inferred you need a brief explanation about The Collatz conjecture.

Explanation:

Put simply, what the Collatz conjecture unsolved problem entails is that if any positive number is picked and it is:

it's equivalent, so we can say that its equal.

let's call the denominator x and the numerador is 18 less then denominator, x - 18.

multiply

2.x = 5.(x - 18)

2x = 5x - 90

90 = 5x - 2x

90 = 3x

x = 90/3

x = 30

so: