Răspuns:
x+y=12=>x=12-y
inlocuim pe x in relatie
[2(12-y)+5y)]/[3(12-y)-2y=15/13
(24-2y+5y)/(36-3y-2y=15/13
(24+3y)/(36-5y)=15/13
13(24+3y)=15(36-5y)
312+39y=540-75y
114y=228=>y=228:114=>y=2
x=12-2=>x=10
