Form the pair of linear equations for the following problem and find their solution by the substitution method.
The larger of two supplementary angles exceeds the smaller by $18^{\circ}$. Find the angles.

(A) Let the larger angle be $x$ and the smaller angle be $y$.
We know that the sum of the measures of angles of a supplementary pair is always $180^{\circ}$.
According to the given information:
$x + y = 180^{\circ}$ $...(1)$
$x - y = 18^{\circ}$ $...(2)$
From equation $(1)$,we obtain:
$x = 180^{\circ} - y$ $...(3)$
Substituting the value of $x$ in equation $(2)$,we get:
$(180^{\circ} - y) - y = 18^{\circ}$
$180^{\circ} - 2y = 18^{\circ}$
$180^{\circ} - 18^{\circ} = 2y$
$162^{\circ} = 2y$
$y = 81^{\circ}$ $...(4)$
Substituting the value of $y$ in equation $(3)$,we get:
$x = 180^{\circ} - 81^{\circ}$
$x = 99^{\circ}$
Hence,the two angles are $99^{\circ}$ and $81^{\circ}$.