Making an environment with the same text color as the background

Question

I am looking to type up some solutions to math problems. However, I do not want someone who just looks at the document to be able to see the solution; I want the students to be able to see the problem without the solution.

How can I create an environment that has the text color the same as the background color?

As an added wrinkle, I do need the color to carry over to the math environment. Thanks for any help.

Answer 1

As mentioned in the comments, there are classes or packages that are probably more suitable solutions (I usually use the exam class). However, one option is to create an environment that sets the color to be the same as the background. Here's an example in a tcolorbox, then again by itself. In the latter case you could just use \color{white} to hide the text.

\documentclass[12pt]{article}
\usepackage[english]{babel}
\usepackage{xcolor}
\usepackage{tcolorbox}
\usepackage[math]{blindtext}
\usepackage{mathtools}

\colorlet{mycolor}{blue!20!white}
\tcbset{colback=mycolor}

\newenvironment{mysolution}
{ Solution:\par\color{mycolor} }
{ \color{black} }

\begin{document}
\begin{tcolorbox}
Problem:

Some problem statement.
\tcblower
\begin{mysolution}
The solution

\begin{equation}
x=2
\end{equation}
\blindtext
\end{mysolution}
\end{tcolorbox}

Problem:

A different problem

\begin{mysolution}
\begin{equation}
y=x^{2}
\end{equation}
\blindtext
\end{mysolution}
\end{document}