Calculation - Help PLEASE

[DrCl]

Hi,

I have a PCR buffer with MgCl2 at 15mM.

I have an additional solution of MgCl2 at 25mM. Using this solution, I would like to increase the MgCl2 concentration of my PCR buffer to 50mM.

How much of this solution do I need to add to the buffer to achieve this final MgCl2 concentration (50mM)?

I really need help with this calculation please!

[MrMistery]

well basically you only need to add an extra 35 mM to the solution, right? So if you calculate it like this:
C1*V1=C2*V2
25*x=35*[whatever your final reaction volume is] and solve for x.
Is that what you mean?