How do you do these? Please be as detailed as possible

Definition: es. this is a disadvantage or weak point that makes someone or something less effective.

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?

Solve each equation using the quadratic formula. find the exact solutions. 6n^2 + 4n - 11