diff --git a/mechanical/mmme1029_materials.md b/mechanical/mmme1029_materials.md
index 6b4ef16..dcd5cbf 100755
--- a/mechanical/mmme1029_materials.md
+++ b/mechanical/mmme1029_materials.md
@@ -39,7 +39,7 @@ tags: [ uni, nottingham, mmme1029, materials ]
 - Thermodynamics indicated that the higher the temperature, the greater the efficiency of heat to
 work:
 
-  $= \frac{T_{high}-T_{low}}{T_{high}}$ (in kelvin)
+  $$ \frac{ T_{high} - T_{low} }{ T_{high} } $$ where $T$ is in kelvin
 
 - The first steam engines were only 1% efficient, while modern steam engines are 35% efficient
   primarily due to improved high-temperature materials.