Answer:
In the drawing we can see that both bars have the exact same size.
Blue bar has 8 tiles, and brown bar has 4.
We can see that every brown tile has the exact same size than two blue tiles.
We paint 6 of 8 tiles in the blue bar and we see that those 6 blue tiles are equivalent to 3 brown tiles, to have the same area painted in both bars.
(because every brown tile has the size of two blue tiles, and 6:2=3)
Then in blue bar we have 6 painted tiles of 8 (6/8) and in brown bar we have 3 pinted tiles of 4 (3/4) being exactly equal both bars and both painted areas.