(690+20x)[(1000+738+72y)/1000]
=(69+2x)(17.38+0.72y)
=[69+2(5-y)](17.38+0.72y)
=(79-2y)(17.38+0.72y)
=1373.02+22.12y-1.44y^2
=-1.44(y-7.68)^2+1288.07
≤1288.07
(690+20x)[(1000+738+72y)/1000]
=(69+2x)(17.38+0.72y)
=[69+2(5-y)](17.38+0.72y)
=(79-2y)(17.38+0.72y)
=1373.02+22.12y-1.44y^2
=-1.44(y-7.68)^2+1288.07
≤1288.07