x+y=20 3x=y用加减消元法来解~

x+y=20 3x=y用加减消元法来解~ 解二元一次方程组：{-8x-5y=0 3x-5y=20要用加减消元法来解 x+y/2+x-y/3=6,4(x+y)-5(x-y)=2用加减消元法解方程组 用加减消元法解三分之x+y+二分之x-y=6,3(x+y)-2(x-y)=28 {x-y=3 2x+3(x-y)=11 用加减消元法解方程组 ｛x-y=3 2x+3(x-y)=11 用加减消元法解方程组 X+2Y+2=0 7X-4Y=-41用加减消元法来解, 30x=0.8y 40(x-1)=y+25用加减消元法来解, 用加减消元法解{x+y=110,40x+20y=2400 用加减消元：x-y=80(1+20%)y-(1-25%)x=30 {3x+5y=3,3x-3y=11用加减消元法解 3x+2y=9 3x-2y=3 用加减消元法解方程组 用加减消元法解方程：｛3x-3y=-6,3x+2y=4; ｛x/3+y/4=1 x/3-y/2=1 用加减消元法解方程组 用加减消元法解方程组3x-2y=1 2x+3y=-7 用加减消元法解方程组{x/3+y/4=2 x/4+y/3=2 用加减消元法解方程组：x+y=3,x-2y=-3 用加减消元法解：4x—3y=14 5x+3y=31