It takes 4 lawnmowers to cut 2 acres of grass in 2 hours. if the amount of time varies directly with the amount of grass and inversely with the number of lawnmowers, how many hours will it take 2 lawnmowers to cut 6 acres of grass?
3
4
8
12

Let, L = Lawn Mower and A = Acre and H = Hours

4L = 2A = 2H
2L = 1A = 1H

We want 6A (acres), we know the amount of lawn mowers doesn't change -
If 1 Acre takes 1 Hour, we know 6 Acres will take 6 hours (when their are 2 lawn mowers). 
Either i'm missing something or the answers are wrong,

The answer is D-12) I just took the test and got it right