Step-by-step explanation:
since you have figured out A already, what is the problem with B ? you "only" need to calculate the perimeter of the shape.
basically the same assumptions as for the area calculations :
the "inner" sides are truly parallel to the line outer sides, so that they are both 12-4=8 m long.
and I assume here in addition that the side with the tiles in front contains a door, which is usually 1 m wide. and for that length we don't need trim of the baseboards (as there are none, where there is a door).
so the needed trim is
12+12+4+8+8+(4-1) = 24+4+16+3 = 47 m
but if my assumption about the door is wrong, then you need to add an additional meter. = 48 m.
and if the side with the tiles does not need any baseboards and corresponding trim at all (for whatever reason), you need to subtract that side completely. = 44 m
