For consumers, pizza and hamburgers are substitutes. A rise in the price of a pizza causes in the equilibrium price of a hamburger and in the equilibrium quantity of hamburgers.

Drugs have a high potential for abuse. there is no routine therapeutic use for these drugs and they are not available for regular use. they may be obtained for “investigational use only” by applying to the u.s. drug enforcement agency. examples include heroin and lsd. which scheduled drug is this?