[tex]\begin{gathered} On\text{ 1st day}\Rightarrow500\text{ people} \\ On\text{ 2nd day}\Rightarrow700\text{ people} \\ \text{percentage change}\Rightarrow\frac{700-500}{500}\text{ }\times100\text{\%} \\ \text{Percentage change}\Rightarrow\frac{200}{500}\times100\text{ \%} \\ \text{percentage change}\Rightarrow40\text{ \%} \end{gathered}[/tex]