PLEASE HELP!!! Which rule explains why these scalene triangles are similar

Answer: Ratio of Parts
Step-by-step explanation:
[tex]\text{Ratio of sides:}\ \dfrac{ST}{WS+ST}=\dfrac{66}{6+66}=\dfrac{66}{72}=\dfrac{11}{12}\\\\\\\text{Ratio of bases:}\ \dfrac{TU}{TU+UV}=\dfrac{44}{44+4}=\dfrac{44}{48}=\dfrac{11}{12}\\\\[/tex]
The ratios are equal so the triangles are similar.