请问由（2100x+700y）/(2100+700)=3% 且（900x+2700y）/(900+2700)=5%怎样推出x=2%,y=5%?

请问由（2100x+700y）/(2100+700)=3% 且（900x+2700y）/(900+2700)=5%怎样推出x=2%,y=5%?
请问由（2100x+700y）/(2100+700)=3% 且（900x+2700y）/(900+2700)=5%怎样推出x=2%,y=5%?

请问由（2100x+700y）/(2100+700)=3% 且（900x+2700y）/(900+2700)=5%怎样推出x=2%,y=5%?
（2100x+700y）/(2100+700)=3%
（900x+2700y）/(900+2700)=5%
化简得525X+185Y=21①
5X+15Y=1②
联立①②得x=2%,y=5%
说句题外话,足下是不是被这个题的整齐性吓到了?就是二元一次方程嘛,还要闹那样?