F^-1(x)= (x-4)/-8 because it's just finding the inverse function
Let us assume the number of student's in Zoe's class = x
Then
Number of students that have pets = 4x/5
Number of students that have rodents as pets = (1/8) * (4x/5)
= x/10
Number of students in Zoe's class
that have pets that are not rodents = (4x/5) - (x/10)
= (8x - x)/10
= 7x/10
I hope that the procedure is clear enough for you to understand and this is the answer that you were looking for.
60 minutes=1 hour
360 minutes=6 hours
so 360 minutes/90 minutes
so your answer is 4 hours
