The Following Set Up Is a System of Simultaneous Linear

The following set up is a system of simultaneous linear equations to allocate costs using the reciprocal method.Matrix algebra is not required.The following costs were incurred in three operating departments and three service departments in Westmoreland Company. $$\begin{array} { | l | r | r | } \hline \text { Department } & \text { Drect Costs } & \text { Label } \\\hline \text { Subassemblies } & \$ 550,000 & \mathrm { P } 1 \\\hline \text { Final assembly } & 776,000 & \mathrm { P } 2 \\\hline \text { Marketing } & 285,000 & \mathrm { P } 3 \\\hline \text { Building occupancy } & 85,000 & S1 \\\hline \text { Research\&development } & 120,000 & \mathrm {~S} 2 \\\hline \text { Supervision } & 45,000 & \mathrm { S3 } \\\hline\end{array}$$ Use of services by other departments is as follows. The equation for department S1 (building occupancy) is:

A) S1 = .10S3.
B) S1 = $85,000 + 1.00S3.
C) S1 = $85,000 + .10S3.
D) S1 = $85,000 + .90S2 + .10S3.