Y varies directly with X if y is equal to some constant with x we could rewrite this in kind of english y varies directly with x if this constant seems strange to you remember this could be literally any constant number so let me give a bunch of examples that would also or particular examples of y varies directly with x you cold have Y is equal to X because of the situation the constant is 1, we didn't even write it you could have write Y is equal to 1X, then K is 1 we could write Y is equal to 2X we could write Y is equal to one half X we could write Y is equal to negative 2X we are still variating directly we could write Y is equal to negative one half X we could have Y is equal to π times X we could have Y is equal to negative π times X