2nd one - y = 3/7x + 6 , hope this helps:)
I can't answer your question without a picture... Sorry.
Answer:
16
Step-by-step explanation:
Given
C=2r and r=8
So
C=2×8 (as r=8)
C=16 (ans)
<u>Answer:</u>

<u>Solution:</u>
Given: x=30
To solve: 
On substituting the value of x,

On dividing 30 and 5 we get,

So, the option is 15.