hm, cross posting definitely seems to give your question a broader exposure, but is not considered to be an appreciated approach when asking for help. but to collaborate on your simple program, this might help:

Code:

float f;
float c;

void setup() {
  size(400, 400);
  background(10, 180, 215);
  PFont fontA = loadFont("Calibri-BoldItalic-48.vlw");
  textFont(fontA, 32);
}  

void draw() {
  // get a fahrenheit value.
  f = mouseX - ( width / 2 );
  // convert fahrenheit into celcius
  c = (f - 32) / 1.8;

  fill(115, 80, 80);
  rect(150, 20, 85, 65);

  fill(215, 180, 180);
  // display the celcius value.
  text("c= "+c, 155, 40);

  fill(175, 17, 250);
  rect(150, 220, 85, 65);

  fill(75, 217, 150);
  // display the fahrenheit value.
  text("f= "+f, 155, 245) ;
}

 

you can easily format source code by putting [code] at the beginning and [/code ] at the end of the code  when posting a message.