x=y+3①2x-y=7②,
①代入②,得2×(y+3)-y=7,
解得y=1,
把y=1代入①,得x=4,
所以,原方程组的解是x=4y=1.
What would you do if you cut yourself _ . [ ]
A. by mistakes
B. by accident
C. by change
在调配色料时,可以把各种不同材料的颜料混在一起。