3x+4y=50,4x+3y=48,那么x+y=?

如果X=3/4Y,那么Y:X=( :) 若3X=4Y,那么X;Y等于 已知4x=5y,那么(3x+y)/(x-2y)= x、y是自然数,规定x@y=4x-3y,那么5@6=? {3(x+y)+3(y+x)=1,3(x+y)+4(y-x)=-1 {3(x+y)-4(x-y)=4 {x+y/2 + x-y/6=1 x+y/2+x-y/3=6,4(x+y)-3(x-y)=-20 {(x+y)/2+(x-y)/3=6 4(x+y)-3(x-y)=-20 4(x+y)-3(x-y)=-20,2/x+y+3/x-y=6 （5x+3y)(3y-5x)-(4x-y)(4y+x)= 3(x+y)-4(x-y)=11,2(x-y)+5(x+y)=27 ｛4/(x+y)+6/(x-y)=3 ｛9/(x-y)-1/(x+y)=1