Modify a float value

Hello, I'm trying for some time now to modify a float value from the new post processing profile but I can't figure out how. I know i need to create a temporary variable but so far I've just used this for positions in which i used Vector3 but now i just need to modify a single float value. I'm trying the line below which is wrong of course. To avoid any confusion my question has nothing to do with the post processing script, i just want to know how to modify a float value that requires to be stored in a temporary variable. PostProcessingProfileScript.bloom.settings.bloom.threshold -= new float (0.05f);