I need to calculate the elasticity coefficient

c. Using the price and quantity you've identified, consider what would happen if this price were to increase by 10%. Estimate the new industry quantity based on your statement in answer a. about whether or not this industry would be elastic or inelastic( I am doing ipads and i said its inelastic in q a) . Calculate the elasticity coefficient based on your price and quantity estimates and the industry revenue before and after the price increase.

i Also am not sure on how to get the ED like (-2.5 or 2.5 etc)

Price: 429$ CAD

Quantity: 12.9 million units

Rev: 5.5 $ (million)

P increased by 10% : 471$

Ed= % Q/ % P (not sure how to calculate this)

please help!