Since the perimeter is four times the side, the constraints on the perimeter are immediately translated into constraints on the side:
[tex] 162 < p < 190 \iff 162 < 4s < 190 [/tex]
So, if you divide every term in the inequality by 4, you have
[tex] \dfrac{162}{4} < s < \dfrac{190}{4} [/tex]
Now simply evaluate the fractions:
[tex] 40.5 < s < 47.5 [/tex]