if above this, take away one..

hi,
i have labels with values from a database.
id like to say: if Label1 is more than Label 55, then Label1s value should be Label1 - 0.5
but if Label1 is less than Label55, then Label1 should be Label1+0.5
How can i write this? label 55 can be a decimal..
if (Label1.Text > Label55.Text)

Label1.Text = ((double.Parse(Label1.Text) - "0.5")
if (Label1.Text < Label55.Text)
Label1.Text = ((double.Parse(Label1.Text) + "0.5")
...