Awsome, thank you, -1.5v does match to 4.7mA. After checking the 2nd answer at 9.2mA that works out for .5v As you say at 21.5v the Transistor would have been destroyed and at -21.5 volts the (correct me please if I'm wrong) the transistor would be off so 0 current. It is a problem with the book or Kindle, I have seen equations not displaying correctly with brackets or symbols missing. If the question was -1.5 and -0.5, then no problem, replacing the 2 in 20.5 or 21.5 with a negative symbol makes everything make sense. Thank again for your help.