Why is the variable and subtraction script in my game countdown not working?

f=60
while game.workspace.Baseplate.egg.looped=true
wait(1)
game.workspace.Message.Text=f
f=f-1
end

This is my countdown script. "Egg" is an audio that is looped and I'm using it as a condition to create a script loop. The trouble code is (I think)

f=f-1

, as everything else here works fine together. Did I mess up with the subtraction code? Is my variable wrong? Does f being not equal to itself mess up the script? Please tell me what I did wrong with the problem code so that I can learn and use the knowledge down the road