Are the values of the Ci also in a data set? Or have you already computed "sum of Ci"?
You posted this to the SAS/IML Support Community, so I will provide a SAS/IML solution. (You can also do this with the SAS data step.)
/* make up sample data */
data Coefs;
input Cn V S A;
datalines;
0.1 4 6 16
;
data Ci;
input C;
datalines;
0.01 0.02 0.03 0.04 0.05 0.06
;
proc iml;
/* read data */
use Coefs;
read all var {Cn V S A};
use Ci;
read all var {C};
/* compute Q */
Q = Cn*V + sum(C)*S / A;
print Q;