PowerPoint is a presentation software that doesn’t provide a lot of options for exporting images in specific dimensions/ DPI. Therefore the following instructions may differ depending on the version and operating system (Mac or Windows) PowerPoint is running on.
In the "Design" tab, click "Page Setup"
In the "Page Setup" window manually enter the dimensions 13.333 in. x 7.5 in.
From the "File" Menu, click "Save As"
In the Save As dialog box, browse to where you'd like to save the files.
At the bottom of the "Save As" dialog box, in the dropdown labeled "Save as Type", choose JPEG (File Interchange Format)
Name the files