Solve the System for X and Y Using Cramer's Rule $\begin{array} { l } \frac { 1 } { a } x + \frac { 1 } { b } y = a b \\x + y = a\end{array}$

Solve the system for x and y using Cramer's rule. Assume a and b are nonzero constants
$\begin{array} { l } \frac { 1 } { a } x + \frac { 1 } { b } y = a b \\x + y = a\end{array}$

A) $\left\{ \left( a b ( 1 - a b ) , a ^ { 2 } \left( b ^ { 2 } - 1 \right) \right) \right\}$
B) $\left\{ \left[ \frac { a ( b - a ) \left( b ^ { 2 } - 1 \right) } { a b ^ { 2 } } , \frac { ( b - a ) ( 1 - a b ) } { a b } \right) \right\}$
C) $\left. \left\{ \frac { a ^ { 2 } \left( b ^ { 2 } - 1 \right) } { b - a } , \frac { a b ( 1 - a b ) } { b - a } \right) \right\}$
D) $\left\{ \left( \frac { a ^ { 2 } b \left( b ^ { 2 } - 1 \right) } { b - a } , \frac { a b ( 1 - a b ) } { b - a } \right) \right\}$