Tidying up a spreadsheet

I have a spreadsheet that needs tidying up.

Part A: In some cells in the Weight column there is a price in brackets, as well as a price in the Price column. For these cases, I want the price that is in brackets to replace the price in the Price column. For example, it might say:
Weight | Price
200g (£2.65) | £1.99

This should change to:
Weight | Price
200g | £2.65


Part B) In the Weight column I need all cells that contain a multiple value to be calculated instead.
For example, 4x22g should change to 88g
4x50ml should change to 200ml.

Please see attached spreadsheet.