Ive just done my first epubcheck in Sigil. Gotta a few questions about the report.

It was particularly unfavorable to my images.
1. Width Value
Col: 163: ERROR(RSC-005): Error while parsing file 'value of attribute "width" is invalid; must be an integer'.
My width value said width="50%" So, whats wrong with that? Doesn't epub like percentages?