Given that the triangles are similar, then their corresponding sides must be in proportion, that is,
[tex]\frac{\text{longest side NOP}}{\text{longest side RST}}=\frac{intermediate\text{ side NOP}}{intermediate\text{ side RST}}=\frac{\text{shortest side NOP}}{\text{shortest side RST}}[/tex]
Substituting with the option, 7.5 cm, 10.5 cm, and 13.5 cm, we get
[tex]\frac{13.5}{9}=\frac{10.5}{7}=\frac{7.5}{5}=1.5[/tex]
