HELP ME PLEASE

Is a positive integer raised to a negative power always positive

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?

If x is 6, then 7x= a. 13 b. 42 c. 42x d. 76