Which file can find these line for w3c valid

[platnumcn]

Anybody know where below codes, tried 30 mins, no results, have to come here for help, Thanks

 

Line 26, Column 3447: required attribute "alt" not specified

…facturer.jpg" width="143" height="62"/><form action="/shop3/index.php" method=…

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The attribute given above is required for an element that you've used, but you have omitted it. For instance, in most HTML and XHTML document types the "type" attribute is required on the "script" element and the "alt" attribute is required for the "img" element.

Typical values for type are type="text/css" for <style> and type="text/javascript" for <script>.

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