Let $\mathrm { a } , \mathrm { b } , \mathrm { x }$ and y be positive numbers such that
$$\begin{aligned}
& \frac { x } { a } \cdot \frac { b } { y } = 2 \\
& \frac { a ^ { 2 } } { x ^ { 2 } } + \frac { b ^ { 2 } } { y ^ { 2 } } = 20
\end{aligned}$$
Given this, which of the following is the value of x in terms of a?\\
A) $\frac { a } { 2 }$\\
B) $\frac { 3 a } { 4 }$\\
C) $\frac { 3 a } { 5 }$\\
D) $\frac { 4 a } { 5 }$\\
E) $\frac { 5 a } { 6 }$