Brain test with math equation

4

There are three balls and their sum is 18. So one ball is 6.

There are three clocks and their sum is 9. So one clock is 3.

There are 3 fans and the equation result is 6. Value for one fan is 3 because 3×3-3=6.

So you would assume that the last result would be 3×6-3=15 and the value to be 15.

It is not like that…

The clock shows 2 o’clock and its value is 2. Also the ball doesn’t have 6 black slices, but it has only 3. It’s value is 3. And the propeller has only two of three blades so it’s value is 2.

The final equation becomes 2×3-2=?

And it’s​ simple now: the final result is 4.