x+y=60000
x-15x/100+y-10y/100=52800, x-3x/20+y-y/10=52800, numitor comun 20 vom avea
20x-3x+20y-2y=1056000
17x+18y=1056000, din prima ecuatie, x=60000-y, inlocuim in a doua
17(60000-y)+18y=1056000
1020000-17y+18y=1056000
y=1056000-1020000=36000lei
x=60000-36000=24000lei