Goi so do la abcd, vi la so chan => d={0,2,4,6}
th1:d=0, a#0
a co 6 cach chon
b co 5
c co 4
=> co 6x5x4 cach lap
th2:d={2,4,6}, a#0
a co 5 cach chon
b co 5
c co 4
=> co 5x5x4 cach lap
kqa = th1 + th2
Các điều hành viên: Admin, Mod, SMod
Goi so do la abcd, vi la so chan => d={0,2,4,6}
th1:d=0, a#0
a co 6 cach chon
b co 5
c co 4
=> co 6x5x4 cach lap
th2:d={2,4,6}, a#0
a co 5 cach chon
b co 5
c co 4
=> co 5x5x4 cach lap
kqa = th1 + th2