Answer:
x = 72 cm
Explanation:
Because the two figures are similar, we can create a proportion between one set of similar sides (i.e., the side measuring 48 cm and the side measuring 6 cm) and another set (the side measuring x cm and the side measuring 9 cm. This, will allow us to solve for x:

Another way to solve would have been to notice that the scale factor used to create the bigger puzzle piece is 8 since 6 * 48. In order for the smaller figure to be considered similar to the larger, every side had to be multiplied by the same scale factor. Since the scale factor is 6, x must be 72 cm as 9 * 8 = 72