longer piece = two times the shorter piece plus 3 feet
L = 2S + 3
Two variables means you need 2 equations. Try adding the two pieces together like so:
L + S = 12 feet
Solve for L:
L = 12 - S
Then Substitute L in the other equation:
(12 - S) = 2S + 3
Solve for S, then put S back into the L = 12 - S equation and solve for L. :-)
