mohon bantuanya kakak yang baik

[tex]C:R:F-32=5:4:9\\ \frac {R}{F-32}=\frac {4}{9} \\ R=\frac {4}{9}\times (F-32)\\ R=\frac {4}{9}\times (80-32)\\ R=\frac {4}{9}\times 48\\ \\ R=21,333\ Reamur[/tex]