Respuesta :

Answer:

RS + ST = RT

23 - 2x     +     9x - 5     =     39

18 + 7x = 39

7x = 39 - 18 = 21

x= 21/7

x = 3

RS = 23 - 2x (given)

RS = 23 - 2(3)

     = 23 - 6

RS = 17