Does solo learn gives course on xhtml ?

Answer 1

No they don't. XHTML is a variant of HTML

Answer 2

XHtml is an abandonned branch of development of Html, more or less equivalent to previous version of Html than actual Html5...
XHtml was abandonned in favour of coming out and development of Html5.
XHtml has less feature, will be from less to less supported, and is more strict on his syntax...

There is no reason at all to teach and/or learn XHtml :P