假設原本有$10, 用$8買雞, 剩$2
% N+ |& q7 s$ A Itvb now,tvbnow,bttvb之後$9賣出, $2+$9 = $11tvb now,tvbnow,bttvb4 Z! E4 \: o# S% @: I. E) \' s) ]
再用$10買雞, $11-$10 = $1
9 \$ ~% h5 x, U( stvb now,tvbnow,bttvb又再以$11賣出, $1+$11 = $12tvb now,tvbnow,bttvb) Q' ^) Y' j) u5 C
$12-$10 = 賺$2 |