Help with word problem
At a unit price of $55 , the quantity demanded of a certain commodity is 1000 units. At a unit price of $85, the demand drops to 600 units. A) given that it is linear , find the demand equation. B) graph the demand equation. C)above which price will there be no demand? D) what is the maximum quantity demanded? E) what is the quantity demanded when the unit price is $65? F) what is the slope of the demand equation? What dose the slope mean in terms of the quantity demanded and dollars?