Joe ate one half of a fifth of a pizza. Gale ate one third of a quarter of that pizza. The difference in the amounts that the two ate was of the pizza, where is a positive integer. Find .
We basically want to prove , or just .
Now since we have , now since we must prove . Now from here we will split the division in prime powers which makes sense due to crt. all hold trivially, the last one from fermat's theorem, therefore we have for all positive integers and ofc when we indeed get which implies the original problem thus we are done .
We have . Clearly, the number is divisible by 8, and we can see that it is also divisible by 11 from the divisibility rule. Now, all we have to show is that it is divisible by 23 now, or that . Since both 8 and 9 are relatively prime to 23, this is the same as showing that This is equivalent to , which is true by Fermat's.