Question 489527
RS is 1/3 RT, therefore ST is 2/3. 
ST is 2x RS.
2(3x -20) = 4x -11
6x -40 = 4x - 11
2x = 29
x = 14.5
3(14.5) - 20 =  43.5 - 20 = 23.5
4(14.5) - 11 = 47
2(23.5) = 47
Cleomenius