4.5

Page 131 29.6.2021

间隔 or
各自组别
The number of ways
(b)
The number of ways

(c)
The number of ways

5 digits The number of ways

2
4
5
6
7

G 12 letters

The number of ways E

(a) The number of ways (Father and mother) + 4 children
(b) The number of ways
n=5

1
2

5 father & mother are
3 seated together

4