X/30+Y/20=1
x-80=y,(1-25%)x+30=(1+20%)y问x=?y=?
已知x+y=30,x-y=20,求1/5(x-3y)²-12.7的值
X/30+Y/20=1
x+y=20-6 3x+y=30
X-[(X*30%+(X-20)*70%)]=X*6%Y/(1+6%Y) x是100 y是多少 还有这个是方程还是什么
1/(x+y)-1/(x+y)=3/20 2/(x+y)+3/(x-y)=19/20 这是
集合N={(x,y)|(x-1)^2}+(y-1)^20},M={(x,y)|x^2+y^2
已知:x-y=1,x+y=-7,求代数式3(x+y)+20(x-y)-5的值
已知x y为实数,且(x+y)(x+y+1)=20 求x+y的值
|x|+|y|=30 2|x|-3|y|=20 求x,y
已知方程组4x+2y=1,20x+8y,求x,y
用加减消元:x-y=80(1+20%)y-(1-25%)x=30