line 1: 3.7x -12y =-186.29... or 37x -120y =-1862.9
line 2: 11x+7.1y =87.8
"eliminashun" is the hard wae
37/11=3.363636363636363
line 2...multipli bi 3.36363 or 37/11
37x +23.8818y =295.324
line 1 - line2...(37x-37x) +(120y+23.8818y) =-1862.9 +295.324
143.8818y=-1567.575
y=-1567.575/143.8818
y=-10.894887
line 2...11x=87.8/7.1y=87.8/-77.3537=-1.1350459
x=-1.1350459/11
x=-0.103186