Answer:
4 shelves
Explanation:
if there is 8 shelves that display 1 car then that means there is 8 cars total.
so if you need a total of 12 cars then you would do (total of cars needed - total of cars you have).
(12-8) which would equal 4.
you need 4 cars left but on each shelf going forward needs to have 2 cars on it.
now since you have 4 cars you would divide that by the amount of cars on each shelf going forward.
4/2) which equals 2.
you need 2 more shelfs for the 4 cars needed.