elasticity of demand

suppose demand for printer is estimated t be Q=1200-5p+3px-4pz+0.3y. if p=50,px=100,pz=70, y=2500

A: what is the price elasticity of demand?

B: what is the cross price elasticity with respect to commodity X?   give and example of what commodity X might  be ?

C: are the printers inferior or normal goods? why 

Healthtermpapers.com