It seems to be a 6x2x5 which equals 60, but we wouldn't be taking out the middle. The empty center would be 5x1x5, which would be 25 bricks. 60 - 25 = 35. There are 35 bricks.
There are 3 rows of 4 bricks per side. And 3 row of 5 bricks per side.
(3(4)+3(5))4=b b= number of bricks
(12+15)4=b
27(4)=108
There are 108 visible bricks