21+50+15=86- V$ c. v8 _$ ^* S
why 86... " L1 c- s- K- ^4 x/ I5 C公仔箱論壇becos he change 50 "small money" then giv bck to customer 29 and he keep the balance 21+ R" Y/ q7 i' f7 ]' w5 V/ l& M
then he giv bck his fren 50 : y& S( @- z+ K* @and the shoes cost is 15www.tvboxnow.com D% w2 O$ e9 y% T
9 P# ?/ {4 o: {! ?7 S% ?3 wtvb now,tvbnow,bttvbso total he loss is 86..." o) M. e. m1 G2 E