система
2x-3y=5
2x+5y=16
2x-3y=5 2x+5y=16 ======== 2x=5+3y 2x+5y=16 =========== x=(5+3y)/2 2x+5y=16 ========== 2((5+3y)/2)+5y=16 5+3y+5y=16 8y=11 y= 1 3/8 x=(5+3*1 3/8)/2=4.5625