Answer:
Yes it is
Step-by-step explanation:
y=-9x means that for every x value, the y value decreases by 9, so it is proportional because the value of y decreases the same amount each time. For example, if x=1, y=-9. If x=5, y=-45, and so on.
Answer: 
Step-by-step explanation:
First, we need to find the common denominator
The easiest way to do this is by multiplying the two given denominators, which are 2 and 5.
2 × 5 = 10
So, our common denominator is 10. Then, multiply the numerators of the two fractions by 2 and 5. Here's why:
=
We multiplied the top and bottom by 2 to make sure our new fraction stays equivalent to the original fraction.
Do the same thing for the other one:
= 
Finally, subtract the two fractions to find the difference between the two times:
= 
The reason we used the common denominator is because we can only add or subtract fractions if they have the same denominator.
Answer:
G. 66 feet
Step-by-step explanation:
Radius = 21/2 = 10.5
Circumference
2 × 3.14 × 10.5
65.94 feet