Here you can keep your brain fit by solving math related problems and also earn SBI by doing so.
The problems usually contain a mathematical equation that in my opinion is fun to solve or has an interesting solution.
I will also only choose problems that can be solved without additional tools, so don't grab your calculator, you won't need it.
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Rules

No upvote, No resteem, No follow required!

I will give 1 SBI to a random person who put a correct solution of the problem in a comment.

You have 48 hours to solve it.

In case there are multiple solutions, you have a higher chance of winning if you get all of them correctly.

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Problem

To remove the obvious solution, I add an additional condition here:
x ≠ y
And one more thing: I only want integer solutions.
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You can take a look at the results of the last contest here.

To everyone who already participated in a past contest, come back today and try a new problem(tell me if you don't want to be tagged):
@addax @ajayyy @heraclio

The contest is over! You can find the results here.