Answer :

[tex]3(4x-3)-7x=5x-9\\ 12x-9-7x=5x-9\\ 5x-9=5x-9\\ x\in \mathbb{R} \Rightarrow B[/tex]
[tex]3(4x-3)-7x=5x-9\\\\3(4x)+3(-3)-7x=5x-9\\\\12x-9-7x=5x-9\\\\\boxed{5x-9=5x-9}\\\\conclusion:\boxed{B.\ infinite\ solutions}[/tex]