Respuesta :

[tex] \frac{2}{3} [/tex]b + 5 = 20 - b   Multiply both sides by 3
2b + 15 = 60 - 3b   Add 3b to both sides
5b + 15 = 60          Subtract 15 from both sides
       5b = 45           Divide both sides by 5
         b = 9