x(4-x)-3(y-x) = 4x-x²-3y+3x = -x²+7x-3y
4х-х^2-3у+3х=-х^2+7х-3у
x+3x/8 +x +3x/8=110
2x+6x/8=110
16x+6x=880 :2
8x+3x=440
11x=440
<u>x=40 kg</u>