Change the order of integration in the double integral: $$ \int\limits_1^2dx\int\limits_{\ln x}^{3x}f(x;y)dy $$
I plotted a picture to make this problem easier. And I managed to see that $0\leqslant y\leqslant 6$. However, I couldn't find the boundaries for $x$.
Could anyone help me, please?