x/3+y/4=0 2(x+y)-3(2y-x)=62 解得x=6 y=-8
5x+6y=13 7x+18y=-1 解得x=5 y=-2
13x+14y=40 14x+13y=41 解得x=2 y=1
2x+3y=3x+2y+20 3(2x+3y)=2(3x+2y)+60 解得x=-5/8 y=12/5
5x+6y=13 7x+18y=-1 解得x=5 y=-2
x-y=8000 (1+0.35)x-(1+0.1)y=11800 解得x=12000 y=4000
(x+2)/3<1 2(1-x)≤5 解得-3/2≤x<1
3x-1>2x+1 -2x<-8 解得x>4
4-5x>-3x+8 3(1-x)>13-5x 无解
3x-15>0 7x-2>8x 无解
x-9(x+2)≤27 5x+9(x+2)≤15 解得-45/8≤x≤-3/14
(2x+1)/3-(1-2x)/2<1 6x-2≥3x-4 解得-2/3≤x<7/10