First, I opened the PowerPoint presentation.
Then I clicked on each picture in turn and clicked 'Save As Picture'. Select the format you want to save your image as, or it will save as an Enhanced Windows Metafile (the default).
It's very important you save as a jpg, gif or png as the Metafile format is not recognised by Blogger. It will reject it, and you'll have to save your images again.
You'll see the results in my post on 1stFloorFlat!