Ru58841 How Long Will It Last, And How Much To Apply?

[NGU]

So i found a bottle of RU58841 on a website I'm not sure Im allowed to post it here, the price is 36 dollars and It is 50 ml with 3 % solution.

I never used RU or anything before and I dont wanna mix It myself since I got 0 knowledge about it.

My question is: How long will this bottle last, how much should I apply each day that is "recommended"

Thank you.