10. There are 50 RMB notes with denominations of 1 yuan, 2 yuan, and 5 yuan. To make their total value 100 yuan, how can the number of notes of these denominations be chosen?
10. $x, y, z$ represent the number of 1 yuan, 2 yuan, and 5 yuan notes respectively. $x+y+z=50, x+2 y+5 z=100$.
$$x=36+3 t, y=2-4 t, z=12+t, t=0,-1,-2, \cdots,-12 \text {. }$$