HELP! guys im so bad at math please help.

Which term best describes the association between variables a and b

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?

Can someone me with the property questions for 12 13 and 14 plz