Solve the following pair of linear equations by the substitution method:

$x+y=14$

$x-y=4$

Solve the following pair of linear equations by the substitution method.

$$$s-t=3 ,$$\frac{s}{3}+\frac{t}{2}=6$

Solve the following pair of linear equations by the substitution method.

$3x-y=3 ,$$9x-3y=9$

Solve the following pair of linear equations by the substitution method.

$0.2x+0.3y=1.3$

$0.4x+0.5y=2.3$

Solve the following pair of linear equations by the substitution method.

$\sqrt{2}x+\sqrt{3}y=0$ , $\sqrt{3}x-\sqrt{8}y=0$

Solve the following pair of linear equations by the substitution method.

$$\begin{gathered} \frac{3x}{2}-\frac{5y}{3}=-2 \\ \frac{x}{3}+\frac{y}{2}=\frac{13}{6} \end{gathered}$$

Form a pair of linear equation for the following problem and find their solution by substitution method.

The larger of two supplementary angles exceeds the smaller by $18$ degrees. Find them.