数学jj

entheticism

ABC xyz 1
A+x+y+1=5
B+y+z+1=6
C+x+z+1=10

A+B+C+x+y+z+1=15

(A+x+y+1)+(B+y+z+1)+(C+x+z+1)= A+B+C+2(x+y+z)+1+2
5+6+10=15+(x+y+z)+2
x+y+z=4

wangxiaoqing

yes, I understand why it is 4 now