X+4Y=8①2X+Y=m②把m先看成一个常数,求出x与y①×2-②得:7y=16-m,y=(16-m)/7①-②×4得:-7x=8-8m,x=(8-8m)/-7要使x与y为正.那么y=(16-m)/7>0x=(8-8m)/-7>0即可.解得:1<m<16