Find the Average Value of the Function F Over the Given

Multiple Choice

Find the average value of the function f over the given region.
- $f ( x , y ) = 9 x + 2 y$ over the rectangle $0 \leq x \leq 3,0 \leq y \leq 9$ .

A) $\frac { 27 } { 2 }$
B) $\frac { 29 } { 2 }$
C) 18
D) $\frac { 45 } { 2 }$