To solve this riddle, let's break down the information provided:

• The cat weighs 10 kg.

• The dog weighs 20 kg.

• When the cat and the mouse are on the scale together, the total weight is 24 kg.

We can calculate the weight of the mouse as follows:

1.  Cat's weight + Mouse's weight = 24 kg
→ 10 kg (cat) + Mouse's weight = 24 kg
→ Mouse's weight = 24 kg - 10 kg = 14 kg

Next, we calculate the total weight of the three animals when the cat, mouse, and dog are together on the scale:

2.  Cat's weight + Mouse's weight + Dog's weight = 10 kg + 14 kg + 20 kg = 44 kg

Therefore, the total weight of the three animals is 44 kg.