Hammer Saw Toolbox Math Puzzle - with Answer

 Hammer Saw Toolbox Math Puzzle

Can you solve the above puzzle and find the value of the fourth image?

ANSWER

27kg is the answer.

Explanation
Let us assume:
a = Hammer;
b = Saw
c = Toolbox

Now the first image becomes:
a + b = 10  --> equation 1

The second image becomes:
b + c = 20  --> equation 2

The third image becomes:
a + c = 24  --> equation 3

Now let us subtract equation 2 & 3
=> (b + c) - (a + c) = 20 - 24
=> b + c - a - c = -4
=> b - a = -4
=> a - b = 4  
=> a = 4 + b --> equation 4

Now let us solve equation 1:
(4 + b) + b = 10    (We replaced a with (4 + b))
=> 4 + 2b = 10
=> b = 3

Now let us solve equation 2:
3 + c = 20
=> c = 17

Now let us solve equation 3: 
a + 17 = 24
=> a = 7

Therefore the fourth image (a + b + c) becomes:
=> 7 + 3 + 17 
=> 27 kg