Not quite!
log4(2x-1) + log4(3) = log4((2x-1)*3)
So we should have
(2x-1)*3 = 5x+12
6x - 3 = 5x + 12
x = 15
Check:
$${{log}}_{{\mathtt{4}}}{\left({\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{15}}{\mathtt{\,-\,}}{\mathtt{1}}\right)}{\mathtt{\,\small\textbf+\,}}{{log}}_{{\mathtt{4}}}{\left({\mathtt{3}}\right)} = {\mathtt{3.221\: \!471\: \!747\: \!924\: \!364\: \!5}}$$
$${{log}}_{{\mathtt{4}}}{\left({\mathtt{5}}{\mathtt{\,\times\,}}{\mathtt{15}}{\mathtt{\,\small\textbf+\,}}{\mathtt{12}}\right)} = {\mathtt{3.221\: \!471\: \!747\: \!924\: \!364\: \!4}}$$
same log base so rewrite
2x-1 + 3 = 5x+12
combine like terms
2x+2=5x+12
get x by it self
3x=10
solve for x
x = 10/3
Not quite!
log4(2x-1) + log4(3) = log4((2x-1)*3)
So we should have
(2x-1)*3 = 5x+12
6x - 3 = 5x + 12
x = 15
Check:
$${{log}}_{{\mathtt{4}}}{\left({\mathtt{2}}{\mathtt{\,\times\,}}{\mathtt{15}}{\mathtt{\,-\,}}{\mathtt{1}}\right)}{\mathtt{\,\small\textbf+\,}}{{log}}_{{\mathtt{4}}}{\left({\mathtt{3}}\right)} = {\mathtt{3.221\: \!471\: \!747\: \!924\: \!364\: \!5}}$$
$${{log}}_{{\mathtt{4}}}{\left({\mathtt{5}}{\mathtt{\,\times\,}}{\mathtt{15}}{\mathtt{\,\small\textbf+\,}}{\mathtt{12}}\right)} = {\mathtt{3.221\: \!471\: \!747\: \!924\: \!364\: \!4}}$$