6. Gary has a rectangular painting that is 21 inches
 wide and 36 inches long. He wants to place wire
 in the shape of an X on the back of the painting
 along its diagonals so that he can hang the 
 painting on the wall. Which is the best estimate
 of the total amount of wire Gary will need?
 42 inches
 84 inches
 57 inches
 114 inches