Use the Following General Linear Demand Relation $Q _ { d } = 680 - 9 P + 0.006 M - 4 P _ { R }$

Use the following general linear demand relation: $Q _ { d } = 680 - 9 P + 0.006 M - 4 P _ { R }$ where M is income and $P _ { R }$ is the price of a related good,R.If M = $15,000 and $P _ { R}$ = $20,the demand function is

A) $P = 690 - 9 Q _ { d }$ .
B) $Q _ { d } = 690 - 9 P$ .
C) $Q _ { d } = 680 - 9 P$ .
D) $P = 680 - 9 Q _ { d }$ .
E) $Q _ { d } = 800 - 19 P$ .