# Math Help - Midpoint?

1. ## Midpoint?

I'm sort of having trouble doing this problem since I don't understand how to do it... Can anyone tell me how to solve this problem?
http://img5.imageshack.us/img5/8251/11934715.jpg

Thanks

2. If T is the midpoint of SU that means that (1/2)SU = ST. You know how to find SU and ST in terms of x, so take it from there.

3. since we have T as the midpoint, by definition ST=TU

so.... $9x=4x+25$

$5x=25$

$x=5$

therefore, ST= 45, because ST=9x=9(5)=45