1.(11/3)x-(2/5)y=9 (7/3)x+(3/5)y=10 x=3 y=5 2.无解6[(2/3)+y]-7(x-3)=6 18(x-3)+5[(2/3)+y]=5 4+6y_7x+21=6 18x-54+(10/3)+5y=5 x=3 y=1/3 3.3(3x-y)-3(x-y)=87 2(3x-y)-3(x-y)=82 x=29/2 y=77/2 4.(3/4)x+2y=(2/...