posted by babygirl .
rs/st=5/7 find the indicated value of x
R 2x+9 S 4x-15 T
You are going to have to explain what you are talking about before help can be provided. Perhaps whatever you typed did not turn out the way you intended. I recommend using / and parentheses for fractions. You never know where the denominators will turn up, otherwise.
if st=15 and rt=40, then rs=