The solution of the simultaneous equations
$$\begin{array} { r }
2 ^ { x } + 3 \times 2 ^ { y } = 3 \\
2 ^ { 2 x } - 9 \times 2 ^ { 2 y } = 6
\end{array}$$
is $x = p , y = q$.
Find the value of $p - q$
A $\frac { 5 } { 12 }$
B $\frac { 7 } { 3 }$
C $\log _ { 2 } \frac { 5 } { 12 }$
D $\log _ { 2 } \frac { 7 } { 3 }$
E $\log _ { 2 } 9$
F $\quad \log _ { 2 } 15$