1)Simplify: 4d - 3e - 9d + 8e

Which expression is not a polynomial?

The u-drive rent-a-truck company plans to spend $13 million on 320 new vehicles. each commercial van will cost $25 comma 000, each small truck $50 comma 000, and each large truck  $80 comma 000. past experience shows that they need twice as many vans as small trucks. how many of each type of vehicle can they buy?

What is the product? a-3/15a × 5/a-3