1.6x=5y300+4x+100=4y2.4(x+y)=805(x-y)=803.y-x=45(85%y-x)8=(y-35-x)x24.0.7(1+40%)x+0.9(1+40%)y=399(1+40%)x+((1+40%)y=4905.x+y/2=502/3x+y=506.x+y=3002.89%乘3x+2.7%乘3y(1-20%)=32338.2-30000
问题描述：
1.6x=5y
300+4x+100=4y
2.4(x+y)=80
5(x-y)=80
3.y-x=45
(85%y-x)8=(y-35-x)x2
4.0.7(1+40%)x+0.9(1+40%)y=399
(1+40%)x+((1+40%)y=490
5.x+y/2=50
2/3x+y=50
6.x+y=300
2.89%乘3x+2.7%乘3y(1-20%)=32338.2-30000
答
第一题,由方程式2化简4y－4x=400,y－x=100即y＝100＋x,代入方程1可得,x＝500,y＝600
第二题,将两个方程式化简即x+y=20,x－y=16,两式相加即x=18,y=2
第五题,x+y/2=2/3x+y即得x=3/2y,代入方程式一,可得x＝75／2,y＝25