I am trying to typeset a worksheet where students will fill in things in blanks. In the below example, they will fill in what they multiply each of the fractions by to get a common denominator. However, the blanks are not aligned with the bottom of the fractions; they are too high. How could I move the fractions up (or resize them) or move the blanks down so that they are aligned?
\documentclass[12pt]{article}
\usepackage{amsmath}
\begin{document}
$$\frac{1}{8}\cdot\underline{\hspace{1.5cm}}=\underline{\hspace{1.5cm}}
\hspace{1cm}
\frac{7}{12}\cdot\underline{\hspace{1.5cm}}=\underline{\hspace{1.5cm}}$$
\end{document}
$$ … $$
for displayed equations. It's plan TeX syntax, and can yield bad vertical spacing.