Change GUI Button text on button press c#

Hello, i was wondering how can i change the GUI Button text when i press the button
i have a mute sound button

if (GUI.Button(new Rect(409, 430, 150, 25), "MUTE", style))
      {
	    audio.PlayOneShot(buttonsound);
      	if(muted == false)
		{
        	AudioListener.volume = 0.0F;
            muted = true;
        }
        else  
		{
            AudioListener.volume = 1.0F;
        	muted = false;
        }
      }

And i want it to change from “MUTE” to “UNMUTE”

string buttonText = “MUTE”;

void OnGUI()
{
if (GUI.Button(new Rect(409, 430, 150, 25), buttonText, style))
      {
        audio.PlayOneShot(buttonsound);
        if(muted == false)
       {
            AudioListener.volume = 0.0F;
            muted = true;
            buttonText = "UNMUTE";
        }
        else  
       {
            AudioListener.volume = 1.0F;
            muted = false;
            buttonText = "MUTE";
        }
      }
}