Solution:

The easiest method to solve this question will be to form equations.

From the first picture
Weight of Cat + Weight of Rabbit = 10 Kg ---- First Equation

From the second picture
Weight of Dog + Weight of Rabbit = 20 Kg ---- Second Equation

From third picture
Weight of Cat + Weight of Dog = 24 Kg ---- Third Equation

Add the first, second and the third equations.

2 (Weight of Cat) + 2 (Weight of Dog) + 2 (Weight of Rabbit) = 10 Kg + 20 Kg + 24 Kg
2 (Weight of Cat + Weight of Dog + Weight of Rabbit) = 54 Kg
Weight of Cat + Weight of Dog + Weight of Rabbit = 27 Kg

Solution:

Move the coins as given in the figure and you will get the required result.

Solution:

Although it looks complicated, the answer is simple. The password to his computer is JIGSAW.
1st letter of Jug = J
2nd letter of Birthdays = I
3rd letter of Fights = G
4th letter of Cars =S
2nd letter of Laptops = A
1st letter of Watch = W

Solution:

Lucky days are here again.

Explanation:
Lucky + Day + s + R + H + Ear + Again (Flower represent lucky symbol)

Solution:

To do this, he must be pushing the cork inside the bottle and then taking out the coin.

Solution:

Tilt the barrel until the fruit juice barely touches the lip of the barrel. If the bottom of the barrel is visible then it is less than half full.If the barrel bottom is still completely covered by the fruit juice, then it is more than half full.

Solution:

The Password.

Explanation:
Clues 2 and 5 are correct and rest are lies.

Solution:

LOTTO

Explanation:
Just flip the two rows 1 and 2 vertically, you will find the word "Lotto".

Solution:

7

Explanation:
8th is bald man head, check the video below.

Solution:

8 liters jar: 8; 5 liters jar: 0; 3 liters jar: 0
Fill 5 liters jar entirely.
8 liters jar: 3; 5 liters jar: 5; 3 liters jar: 0
Fill 3 liters jar with 5 liters jar.
8 liters jar: 3; 5 liters jar: 2; 3 liters jar: 3
Pour entirely from 3 liters jar to 8 liters jar.
8 liters jar: 6; 5 liters jar: 2; 3 liters jar: 0
Pour entirely from 5 liters jar to 3 liters jar.
8 liters jar: 6; 5 liters jar: 0; 3 liters jar: 2
Fill 5 liters jar with water from 8 liters jar.
8 liters jar: 1; 5 liters jar: 5; 3 liters jar: 2
Fill the 3 liters jar with water from the 5 liters jar.
8 liters jar: 1; 5 liters jar: 4; 3 liters jar: 3
Empty 3 liters jar in 8 liters jar.
8 liters jar: 4; 5 liters jar: 4; 3 liters jar: 0

Now you have 4 liters of water in 8 liters jar as well as 5 liters jar.

Solution:

White should move the rook from
A1 to D1 and hence complete the castling move.