Answer:
40 cm²
Explanation:
The image was not clear on one of the blocks. I took that block as being attached to the bottom row at the back
The unpainted surfaces would be the ones that are not facing outside
Block on the extreme left: Has only one surface untouched by paint (1)
The block next to it has 3 surfaces untouched by paint- two of them on its left and right and one at the back (3)
The block on the extreme right has only one surface unpainted (1)
The block on the immediate left of this block has 3 surfaces unpainted (3)
The block above it has one surface unpainted (1)
The block behind has one surface unpainted (1)
Total number of unpainted surfaces = 1 + 3 + 1 + 3 + 1 + 1 = 10 surfaces unpainted
The area of each surface = 2 x 2 = 4cm²
So total surface area unpainted would be 4 x 10 = 40 sqcm