Giải hệ phương trình: \(\left\{ \begin{array}{l}\dfrac{1}{x} + \dfrac{1}{y} = \dfrac{3}{4}\\\dfrac{1}{{6x}} + \dfrac{1}{{5y}} = \dfrac{2}{{15}}\end{array} \right.\).
A.\(\left( {x;y} \right) = \left( {4;2} \right)\).
B.\(\left( {x;y} \right) = \left( {2;4} \right)\).
C.\(\left( {x;y} \right) = \left( {1;-4} \right)\).
D.\(\left( {x;y} \right) = \left( {-1;-a} \right)\).