1/5 is the rule
Sam's shorts were 3/7 of the rule. Thus Sam's shorts, being 6 inches, were 3/7 times 1/5 or 3/35 off the rule.
Now, ask yourself, 3/35 of something must equal 6. Guess what it is.
Now, some people might think the word "something" could be misconstrued as a variable. If that be the case, I guess I used algebra to solve it.