Help system

Rewrite the second equation to $3a + 2b - mb = k$.

Now, factor out b to get $3a + (2-m)b = k$. 

For the system of equations to have an infinite number of solutions, the 2 equations must be identical. 

This means that $2 -m = 2$, so $\color{brown}\boxed{m = 0}$ and $\color{brown}\boxed{k = 2}$