The formula of product's price elasticity is calculated by % Change in Quantity Demanded / % Change in Price.
% Change quantity Demanded= ($ 75 - $60) / $60 x 100%
= 25 %
% Change in price = ($80 - $100)/ $100 x 100% = -20%
product's price elasticity = 25/20 = 1.25 ( economists often drop the negative sign and express the price elasticity of demand as a positive number)
