第1个回答 2013-08-06
2A+8B=35A-7xB,x=(33A-8B)/7B
15A+5B=9yB-18A,y=(33A+5B)/9B
x/y=9(33A-8B)/7(33A+5B)=(297A-72B)/(231A+35B)=(297A/B-72)/(231A/B+35)
2x+y=2(33A-8B)/7B+(33A+5B)/9B=18(33A-8B)+7(33A+5B)/63B=(825A-109B)/63B=825/63 *A/B-109/63=1,A/B=172/825代入上式