bencake

題目誤導人~
5 F% W- o$ H; w% I- }. j! h3 D: y# R公仔箱論壇owner 100
7 _: B3 H8 F# B- [3 r+ Qowner's son 20
9 w! [$ a4 y  m6 A; g  H, f公仔箱論壇each pay 40; I/ }+ [  ~+ q7 ], f
40*3 = 120& g: G$ N, h9 W) s" G3 X
120(3 guys) - 20(owner's son) = 100 (owner)