Răspunsuri

2014-04-16T14:42:04+03:00
(x+y)/(x-y)=3/5
20%x=3+25%y
20x/100=3+25y/100 (aducem la acelasi numitor)
20x=300+25y
20x-25y=300
5(4x-5y)=300
4x-5y=300/5=60
x=(60+5y)/4
Inlocuim in prima ecuatie: (x+y)/(x-y)=3/5
[(60+5y)/4+y]/[(60+5y)/4-y]=3/5
[(60+5y+4y)/4]/[(60+5y-4y)/4]=3/5
[(60+9y)/4]*[4/(60+y)]=3/5 (4 se simplifica)
(60+9y)/(60-y)=3/5 (Inmultim pe diagonala)
5(60+9y)=3(60-y)
300+45y=180-3y
300-180= -3y-45y
120= -48y
y= -120/48
y= -2.5

Si x=(60+5y)/4
x=(60-12.5)/4=47.5/4=11.8