(40-x)(50 2x)=300

x加30%x=521.3x=52x=52×1.3x=40x减40%x=150.6x=15x=15÷0.6x=2550%x加x=31.51.5x=31.5x=31.5÷1.5x=21x减1%x=19.8

30%x+44.2=51.130%x=6.90.3x=6.9x=23x+35%x=91.35x=9x=20/3x-40%x=3.60.6x=3.6x=6

X/(x-30)=(x+40)/XX^2=(X-30)*(X+40)X^2=X^2+40X-30X-120010X=1200X=120

原方程可化为100*{(X+X*20%)-[(1200-X)-(1200-X)*20%]}=40%*100100*120%X-100*[(1200-X)-(1200-X)*20%]=40120X-10

1:x=(52)/(1.3)2:x=(15)/(0.6)3:x=x=(31.5)/(1.5)4:x=(19.8)/(0.99)

X=32

X+X*20%-(1200-X)-(1200-X)*20%=40%,等式左右同时乘以100得100X+X*20-100*(1200-X)-(1200-X)*20=40120X-(1200-X)*120

（X+X)+(X-X)+(X*X)+(X/X)=1002X+0+X*X+1=1002X+X*X=99X(X+2)=99X=9再问：请问X(X+2)=99解为什么就等于9了呢没看懂再答：换成算术法你就明

X+30%X=52(1+30%)x=521.3x=52x=52÷1.3x=40X-10%x=27(1-10%)x=270.9x=27x=27÷0.9x=3020%x+24=4020%x=40-240.

25%x=750.25x=75x=75/0.25x=30060%x-35%x=1250.6x-0.35x=1250.25x=125x=500x-40%x=12060%=1200.6x=120x=200

x除55%=100x=100×0.55x=5560%x=30x=30×5/3x=50x+50%x=4.51.5x=4.5x=3（1-25%）x=723/4x=72x=72×4/3x=964x+40%x

1.5x=30x=20再问：过程再答：x+0.5x=301.5x=30x=20

中间是乘号吗?750/x²=15/x显然x不等于0则两边乘x²750=15xx=50

60%x+25=400.6x=40-250.6x=15x=25x+30%x=521.3x=52x=4019-120%x=719-7=1.2x1.2x=12x=10x-10%x=180.9x=18x=2

30%x=12030x=12000x=400x-60%x=16040%x=16040x=16000x=400120x-20x=40100x=40x=0.450%x-33%x=3417%x=3417x=

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x-30%x=1470%x=14x=20x+25%x=20125%x=20x=16

X/50+(40-X)/30=1同乘1503x+5(40-x)=1503x+200-5x=150-2x=-50x=25

移项0.25x+0.25x+0.6x-x=300.1x=30x=30÷0.1x=300

问题是不是X2=(X+30)*(X-18）啊?要是上面的话就这样X2=X*X-X*18+30*X-30*18=X2+12X-540移项得：X2-X2-12X=-540,即-12X=-540,X=45*