Problem: a block of wood has dimensions 10 cm x 10 cm x 40 cm . the block is painted red and then cut evenly at the 20 cm mark , parallel to the sides , to form two rectangular solids of equal volume . what percentage of the surface area of each of the new solids is not painted red ? 
Options: a ) 5 % , b ) 10 % , c ) 15 % , d ) 20 % , e ) 25 %
b