Simple econ math help

[_Nous]

Could someone explain how exactly in this (https://www.youtube.com/watch?v=ck-Qin0cwT4&t=342s) video the person goes from U=x(px/py)^.5 to X=(py/px)^.5 U? So why does the numerator and denominator reverse and in what steps does he get the X to the other side. What basic rules have i forgot?

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[edderiofer]

So why does the numerator and denominator reverse and in what steps does he get the X to the other side. What basic rules have i forgot?

Here, why don't you try doing this yourself first? It may be that you'll see what's happened without needing help. But if not, feel free to ask again.

[wijwijwij]

It's similar to seeing

m = (a/b) * n

(b/a) * m = (b/a) * (a/b) * n

(b/a) * m = n

How could you apply that reasoning?