Part 13 says to half a difference. You have written a difference there, but have you halved it?
Part 17 says ten more. When you go to a shop and ask for sweets, the shopkeeper gives you one sweet. Then you ask for ten more, how many sweets will you have in total? Try re-doing that now.
Now work on ones you haven't done:
Part 5 you should know - you already did it in a previous part.
Part 6 - First figure out what the square of x means. Then you want 5 lots of that. So if you want 5 lots of a bunch of bananas. What does that mean? It means you get 5 bunches of banans - but you have more than 5 bananas because each bunch has a few.