When the local cinema increased its ticket prices from $20 to $24, there was a 10% decrease in quantity demanded for a nearby popcorn seller. Calculate the cross-price elasticity of demand. ( Ec = %AQ. / %APb ) (Hint: You need to firstly calculate the percentage change in the cinema's ticket prices.) Remember for this elasticity the negative or positive sign is very important so you need to put the correct sign with your number. (Note: do not put a space between the sign and the number; e.g. not - 2.5 but -2.5). (Also do not type in calculation working ; just type in your final answer as a number.)