The image shows a pyramid of boxes. The value in each box is the sum of the two boxes directly above it. Fill in the empty boxes.

This box is the sum of the two boxes above it.

$$74 \text{ kg} + 42 \text{ kg} = 116 \text{ kg}$$

The first empty box is $\boxed{\text{116 kg}}$.

Let this empty box be $X$. The box below 39kg and $X$ is 59kg.
So, we set up the equation:

$$39 \text{ kg} + X = 59 \text{ kg}$$

To find $X$, subtract 39kg from 59kg:

$$X = 59 \text{ kg} - 39 \text{ kg}$$ $$X = 20 \text{ kg}$$

The empty box to the right of 39kg is $\boxed{\text{20 kg}}$.

This box is the sum of the two boxes above it.

$$45 \text{ kg} + 25 \text{ kg} = 70 \text{ kg}$$

The empty box below 45kg and 25kg is $\boxed{\text{70 kg}}$.

The last two empty boxes (one to the right of the bottom-most 25kg, and the one below them) cannot be determined with the information provided in the image, as there are no additional values given to complete those calculations.