(first problem) The 8cm is pointless it just give extra unneeded info a little trick my techer taught me is when you dealing with parellelagrms what you should do is see the dotted line well move the shape the is on the left side of the dotted line to the right side of the parrallelagram and now its a rectangle so all you need to do is 9cm x 24cm = 216cm
I dont think i can help with the secound one sorry but does this help?
