\documentclass[12pt,a4paper]{article} \usepackage[spanish]{babel} \usepackage{amsmath} \title{Tema I: Ejercicio I} \author{Nicolás A. Ortega Froysa} \begin{document} \maketitle \begin{align*} d_{p} = \sqrt{1080^{2} + 1920^{2}} = 2202.907 \simeq 2203 \\ d_{i} = 40 \\ PPI = \frac{d_{p}}{d_{i}} = \frac{2203}{40} = 55.075 \end{align*} \end{document}