tyre and tube query urgent

lucky sharma (212 Points)

15 January 2019  
I am dealer of tyre and tube . In gst bill received tyre @ 28% and tube @ 18%. . so my question is I made only b2c supply and both tyre and tube sale jointly not separate so I charge 28 % for both ( mixed supply ) or charge 28 % for tyre and 18 % for tubes. please suggest me . please it's urgent