公鸡x只,母鸡y只,小鸡z只得出不等式20>x>030>y>0100>z>0方程组：（1）5x+3y+z/3=100=>15x+9y+z=300（2）x+y+z=100=>z=100-x-y2带入115x+9y+100-x-y=300=>14x+8y=200=>7x+4y=100=>y=(100-7x)/4=>y=25-7x/4y为整数,所...