Please answer this correctly

13

Step-by-step explanation:

Find the scale factor by 39 / 30

Take that times 10

1.3 x 10 = 13

Since the questions states these two shapes are "similar" the side will have identical scale factors.

Divide the longest side of the bigger shape to the smaller shape.

39 / 30 = 1.3

The scale factor is 1.3.

Now, multiply the shortest side if the smaller shape by the scale factor.

10 * 1.3 = 13

Therefore, the length of w is 13mm

Best of Luck!