Each pack of dvds costs w dollars. If there is a discount of x dollars on each pack How much do you have to pay to buy each pack?
Each pack of dvds costs w dollars. 

This means that if we have one pack, it will cost w dollars. 

If we have two packs, it will cost 2w dollars. 

If we have three packs, it will cost 3w dollars. 

Now, if we have a discount of x dollars on each pack, this means that for each pack, we will pay w - x dollars. 

So if we have one pack, we will pay w - x dollars. 

If we have two packs, we will pay 2(w - x) dollars. 

If we have three packs, we will pay 3(w - x) dollars. 

I hope this helps!