In triangle $RST$, the length of $RS$ is $21$, and the length of $ST$…

Question

Prompt

In triangle

R S T

, the length of

R S

21

, and the length of

S T

9

. Triangle

R S T

is dilated by a scale factor of

\frac{1}{3}

to obtain triangle

R^{'} S^{'} T^{'}

. What is the length of

S^{'} T^{'}