Thought bubble in latex

Question

I wish to draw illustration nodes with text box as shown, But my latex is poor. Any startups?

Answer 1

This is an attempt where tikz pic is used with cloud shape from tikzlibrary. One might to play with cloud puff arc=110, aspect=2 in the cloud/.pic definition for one's like . Furthermore, the node (c1) and (c2) are adjustable to place the two clouds.

Edit: Replace the aspect=2 key by cloud ignores aspect key will yield

Code

\documentclass{article}
\usepackage[left=0in,top=2in]{geometry}
\usepackage{tikz,amsmath}
\usetikzlibrary{arrows,shapes}

\newcommand{\tikzmarkC}[1]{\tikz[overlay,remember picture,baseline={-3pt}] \node[] (#1) {
};}

\tikzset{cloud/.pic={
\node[cloud, cloud puffs=10.8,cloud puff arc=110, aspect=2, draw, text width=3cm
    ] () at (0,0) {\tikzpictext};
}}
\begin{document}

\begin{flalign*}
6x^2+9x-8x-12&=3\tikzmarkC{a}x(2x+3)-\tikzmarkC{b}4(2x+3)\\
&=(3x-4)(2x+3)
\end{flalign*}

\begin{tikzpicture}[overlay,remember picture]
\pic (c1) at (15,5) [pic text=$3x$ is a factor of both $6x^2$and $9x$]{cloud};
\pic (c2) at (17,1) [pic text=$-4$ is a factor of both $-8x$ and $-12$]{cloud};
\draw[-latex'] (c1) to[bend right] (a);
\draw[-latex'] (c2) to[bend left]  (b);

\end{tikzpicture}
\end{document}