I wish I’d spent more time as a kid doing mental math.

I’m terrible at it, but it is a useful skill despite having a phone in my pocket almost all the time.

I would never have guessed that result! What a weird coincidence.

I’m sure there are lots of little coincidences like this.

Taking x=10, the top of the fraction simplifies to:

5x² + 20x +30

The rest of the solution is left as an exercise for the reader.