设用x张白铁皮做盒身,y张白铁皮做盒底
x+y=36
2*25x=40y
由x+y=36,y=36-x
代入2*25x=40y
2*25x=40(36-x)
50x=1440-40x
90x=1440
x=16
y=36-x
=36-16
=20