1,20x+11,20-1,40x=10
3x-5y=11 2x+7y=-3
90t+120t=420
4x+y=10 -5x-2y=-11
2x-3y=-5 -x+6y=7
X^2+6x-187=0
X1=11, x2=-17
X=3, y=-2
X=-1, y=1
X=2, y=-1
X=6
t=2
