小六數學:計算式

A+B=18 (1式)
B+C=24 (2式)


2式-1式
C-A=6 C比A多6元

A+C=12
哪代表A=3 C=9 (3式)

代3式去第1或第2題
3+B=18
B=15

A+B+C=15+9+3
27

答案是27

ans: $27

let A has $a, B has $, C has $c,
a b=18
b c=24
a c=12

(a b) (b c) (a c)=18 24 12
2*(a b c)=54
(a b c)=27

where a+ b+ c = the sum of money that A,B & C have

2008-07-12 12:32:25 補充：
a+ b=18
b +c=24
a +c=12

(a+ b)+ (b+ c)+ (a+ c)=18 24 12
2*(a+ b +c)=54
(a+ b +c)=27

2008-07-12 12:32:59 補充：
(a+ b)+ (b+ c)+ (a+ c)=18 +24+ 12

sorry
忘記打加號