To calculate the own-price elasticity of demand (PED), we can use the formula:

$E_d = \frac{\% \text{ change in quantity demanded}}{\% \text{ change in price}}$

This can be rewritten as:

$E_d = \frac{\Delta Q / Q}{\Delta P / P}$

where:

• $\Delta Q$ is the change in quantity demanded,
• $\Delta P$ is the change in price,
• $Q$ is the initial quantity demanded, and
• $P$ is the initial price.

Since you haven't provided the actual demand equation, I need to know the specific demand function to calculate the quantity demanded at the initial price of $30 and the new price of $25.

Could you please provide the demand equation? It should be something like $Q = a - bP$, or similar. Once I have that, I can compute the elasticity for you.