Let 'p' represent the number of pants and let 's' represent the umber of shirts.
Since the store can buy up to a total of 500 pants and shirts each month, the first inequality is:
[tex]s+p\le500[/tex]then, the store wants to buy at least as many shirts as pants, then this can be represented with the following inequality:
[tex]s\ge p[/tex]finally, the store wants to buy at least 100 pants each month, then:
[tex]p\ge100[/tex]therefore, the system of inequalities is:
[tex]\begin{gathered} s+p\le500 \\ s\ge p \\ p\ge100 \end{gathered}[/tex]