Ok so the concentration of my dilution from my lab was 5.

Ok so the concentration of my dilution from my lab was 5.26E-6 and the post lab problem is asking me to calculate the concentration of the stock solution given the concentration of my dilution and my dilution scheme. My dilution scheme was 2.5 ml of stock with 22.5 ml water. I am stuck on how to calculate the concentration of stock given all of this. thanks