HALPPPP! For a certain value of $k,$ the system \begin{align*} 3a + 4b &= 7,\\ 6a + 4b &= k- 4b \end{align*}has infinitely many solutions $(a,b).$ What is $k$? I had this question on my math test. Got my results, but they didn't tell me correct answer. Plz tell me correct answer with steps so i know how i got it wrong.
