Question 157353
Sometimes the problems are so obvious you may think they want something more.
1.{{{RT=5}}} Given statement
2.{{{RS=5}}} Given statement
or {{{5=RS}}} Restate (re-arrange) no.2.
{{{RT=5=RS}}} Two things equal to the same thing are equal to each other. 
{{{RT=RS}}} Cut out the middle to simplify.