Update page.en.md

01.curriculum/01.physics-chemistry-biology/03.Niv3/02.Geometrical-optics/05.paraxial-optics/02.paraxial-optics-simple-elements/02.spherical-refracting-surface/07.spherical-refracting-surface-level-up/page.en.md

@@ -5,8 +5,9 @@ visible: false
 ---
 
 course : level+1
-- or level+1 if current level = 1
-- or level-2  if current level = 4
+
+\- or level+2 if current level=1
+\-or level-1 if current level=4
 
 #####for parallel or other level course :
 It will be possible to redirect towards an other page in the m3p2 cursus.