Đáp án:
x- $\frac{1}{2005}$ =3- $\frac{y}{2006}$
⇔x= 6016/2005-y/2006
=> 6016/2005-y/2006-y=4009
⇔y=-4004,003488
=> x=4,9965
2) 3x=2z=> x=2/3 z
4y=5z=> y=5/4 z
x-y+z=5/12 z=61
z=732/5
x=488/5
y=183
3) 4x=7y=3z
=> x=3/4z
7=3/7z
x+y+z=3/4z+3/7z + z=61
z=28
x=21
y=12