Non-Elementary Integration · Easy problem

Frullani's theorem: if $f$ is continuous on $[0,\infty)$ and $f(x)\to f(\infty)$ as $x\to\infty$, then $\displaystyle\int_0^{\infty}\dfrac{f(ax)-f(bx)}{x}\,dx=\bigl(f(0)-f(\infty)\bigr)\ln\dfrac{b}{a}$ for $a,b>0$. Evaluate $\displaystyle\int_0^{\infty}\dfrac{1}{x}\left(\dfrac{1}{1+2x}-\dfrac{1}{1+3x}\right)dx$.