Let there are x pets in the store. So 90% of all pets means that 0.9x.
The equation for the dogs anf total pets in the store is,
[tex]0.9x=54[/tex]Simplify the equation to obtain the value of x.
[tex]\begin{gathered} 0.9x=54 \\ x=\frac{54}{0.9} \\ =60 \end{gathered}[/tex]So there are 60 pets in the pet store.