Answer:
C
Step-by-step explanation:
We know it's direct variation using the direct variation equation.

Where k is the constant.
Since 7 times x is the y values, 
Now we can substitute 7 into k of the direct variation equation.

Answer:
to estimate the result of multiplication (product), round the numbers to some close numbers that you can easily multiply mentally. One method of estimation is to round all factors to the biggest digit (place value) they have.
Step-by-step explanation:
C=2πr r radius it would be right