Solution: Let a man be X, a woman be Y and a child be Z.
According to the meaning of the question
x+y+z=30
Because * * * spent 50 shillings, each man spent 3 shillings, each woman spent 2 shillings, and each child spent 1 shilling.
Get 3x+2y+ 1z=50.
That is, solving binary linear equations:
x+y+z=30
3x+2y+ 1z=50
By using the exhaustive method, we can get
x y z
1 18 1 1
2 16 12
3 14 13
4 12 14
5 10 15
6 8 16
7 6 17
8 4 18
9 2 19