Lets do
[tex]\\ \Large\sf\longmapsto 150:450:750[/tex]
[tex] \\ \Large\sf\longmapsto \frac{150}{ \dfrac{450}{750} } \\ \\ \Large\sf\longmapsto \frac{15}{ \dfrac{45}{75} } \\ \\ \Large\sf\longmapsto \frac{3}{ \dfrac{9}{15} } \\ [/tex]
Simplified ratio is
[tex]\boxed{\LARGE{\sf \$1:\$3:\$5}}[/tex]
