Seeking: the procedure of solving the inequality of linear equation of one variable

Seeking: the procedure of solving the inequality of linear equation of one variable

For example: 2x + 3Y = 12 1
X - y = 6 2
1 minus 2 = = = x + 4Y = 6, change it into x = 6 - 4Y and substitute it into 2
Y =0
X=6