15-6= 9
30-6= 24
24+9= 33
50-33= 27
27 students are taking neither class I think
Answer:
There are 9 000 000 = 9 million reptiles in the US.
Step-by-step explanation:
Percentages and ratio:
The double of a measure, for example, is 200% of the measure.
So 1000% of a measure is 10 times the measure.
There are 90 million pet dogs in the US. The number of dogs is 1000% the number of reptiles.
The number of pet dogs is 10 times the number of reptiles, which means that:



There are 9 000 000 = 9 million reptiles in the US.
1,4,6
4 because 2:1 is equal to 4:2. 6 because 3:1 is equal to 6:2
OK, this written in numbers is

But, fractions can not divide. So we need to multiply one by the reciprocal of the other. The reciprocal of a fraction is itself flipped upside down. For example, the reciprocal of 1/2 would be 2/1.
So, we will multiply 3/2 by 4/1. We know how to do this, it is simply 3/2*4=12/2=6.
So, the answer is n = 6. That would be answer c, because 6 is between 5 and 7.