a) 7! = 7*6*5*4*3*2*1 = 5040 different ways
b) 7C4 = 7! / (4!3!) = (7*6*5) / (3*2*1) = 35 ways
c) See above 4*3*2*1 = 24 ways
Your answer is correct because the ABCD rectangle is solved like this:
4x2=8
2x2=4
8+4=12
Answer=12
EFGH rectangle is solved like this:
8x2=16
6x2=12
16+12=28
Answer=28
Both rectangles have different answer and size so they are definitely not similar so you are DEFINENTLY RIGHT! Lol!