Draw the graphs of the equations x - y + 1 = 0 and 3x + 2y - 12 = 0. Determine the coordinates of the vertices of the triangle formed by these lines and the x-axis, and shade the triangular region.

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

x + y = 14 and x - y = 4

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

3x - y = 3 and 9x - 3y = 9

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

0.2x + 0.3y = 1.3 and 0.4x + 0.5y = 2.3