Your equation is like so A x 2 x 3 = 132
A is the length of your first string B is the length of your 2nd string (A x 2) and C (3) is the length of your 3rd string which is (A x 3).
A x 2 x 3 = 132
/3 /3
A x 2 = 44
/2 /2
A = 22.
A(22) x 2 x 3 = 132. 22 x 2 is 44. 44 is the length of line 2. 22 x 3 is 66, 66 is the length of line 3. 22 + 44 + 66 = 132. 66 is the length of your longest piece.