Answer:
since the price elasticity of demand for students is -4, the the price charged to them should be:
price = [-4 / (-4 + 1)] x $6 = (-4 / -3) x $6 = $8
since the price elasticity of demand for faculty is -2, the the price charged to them should be:
price = [-2 / (-2 + 1)] x $6 = (-2 / -1) x $6 = $12