Switch\:sides
-9s<-72
\mathrm{Multiply\:both\:sides\:by\:-1\:\left(reverse\:the\:inequality\right)}
\left(-9s\right)\left(-1\right)>\left(-72\right)\left(-1\right)
\mathrm{Simplify}
9s>72
\mathrm{Divide\:both\:sides\:by\:}9
\frac{9s}{9}>\frac{72}{9}
Simplify
s > 8
[tex]\\ \tt\longmapsto -72>-9s[/tex]
[tex]\\ \tt\longmapsto 9s>72[/tex]
[tex]\\ \tt\longmapsto s>8[/tex]
Or
[tex]\\ \tt\longmapsto s\in(8,\infty)[/tex]
