2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/170411Let $M$ be a compact 3-manifold with a triangulation $τ$. We give an inequality relating the Euler characteristic of a surface $F$ normally embedded in $M$ with the number of normal quadrilaterals in $F$. This gives a relation between a topological invariant of the surface and a quantity derived from its combinatorial description. Secondly, we obtain an inequality relating the number of normal triangles and normal quadrilaterals of $F$, that depends on the maximum number of tetrahedrons that share a vertex in $τ$.7 pages, 1 figureGeometric Topology57Q35 (Primary), 57M99 (Secondary)text