* Volumes and weights must be expressed in the same units
* Concentrations must be expressed in the same units

A. FORMULA:
 
        V C = V1 C1

B. FORMULA:

       W C = W1 C1

V     =    Volume of stock preparation
C     =    Concentration of stock praparation
V1   =    Volume of stock preparation
C1   =    Concentration of desired preparation
W    =    Weight of stock preparation
W1  =    Weight of desired preparation