Answer:
42 inches
Step-by-step explanation:
Im guessing that the the table looks like this:
Width Length
3 7
6 14
9 21
So we can see the numbers on the right are increasing by 3 and the numbers on the left are increasing by 7.
The width is 3 times some number, and the length is 7 times the same number.
So if the width was 18 then we know the number would be 3 because 3 * 6 = 18
If that number is 6, then the length will be 6 * 7 = 42
So the length is 42 inches

looking at the picture above... you do have the radius, is just in the truncated part of the picture... so you have "h" and "r", so just plug them in
Divide it and you will have the answer or use calc