Question 900321
L = 3W-11
L * W = A
You can do this algebraically by substituting the value of L from the top equation into the bottom, but there's an easier way.
One of the factor sets of 42 is 7/6.  You can tell right away that those are the correct numbers just by looking at the problem.  
Prove it:
7 = 3(6) - 11
7 = 18-11
7 = 7