It doesn't seem likely that a PowerPoint presentation (.pptx) can be directly converted to Excel spreadsheet (.xlsx) as these two document formats serve different purpose. You can of course copy the tables, text or images from a .pptx file to .xlsx when you open the presentation in PowerPoint and copy and paste what you need to to Excel, but that is not pptx to xlsx conversion in proper sense.
Open PPTX file Open XLSX fileAn universal picture and document converter
Office suite app for BlackBerry devices
Official release of Microsoft Office optimized for Google Android operating system
Microsoft office suite optimized for Windows Phone operating system
One of the many available document converters