Answer :
[tex]\frac{30\ cars}{45\ minutes} = \frac{10\ cars}{15\ minutes} = \boxed{\frac{40\ cars}{60\ minutes}}[/tex]
I think it is 90 because u have to find out how many cars they wash in one minute(1.5). Then u multiply it by 60 cause they need to know how many in a hr so I think it's 90 cars
