7. [4] The price-demand equation for gourmet hamburgers at Red Robin restaurants is x(p) = 8000 -400p a) If the current price of a hamburger is $11. Find the elasticity of demand. b) Is demand elastic, inelastic or have unit elasticity at this price? Page 6 of 7 c) Will a 10% price increase cause the revenue to increase or decrease? d) If price is increase by 10% from $11, what will be the approximate percentage change in the demand