Veribles are not assigned... kind of?

Can someone tell me why this isn’t working?

Robert is a man.
Robert has a number called friendship that varies.
Robert has a number called max friendship. 
Max friendship is usually 100.
Friendship is 25.

I’m getting this error:
Problem. You wrote ‘Friendship is 25’ : but this seems to say that a thing is a value, like saying ‘the chair is 10’.

It’s a number! I just defined it two lines above. Why is this bombing?

Max friendship and friendship are properties of Robert, so you have to say “max friendship of Robert”. Inform doesn’t know what “max friendship” means alone, so it assumes it is an object.

Also, your code defines a property called “friendship that varies”. You probably don’t want the “that varies”.

Robert is a man.
Robert has a number called friendship.
Robert has a number called max friendship.
Max friendship of Robert is usually 100.
Friendship of Robert is usually 25.

What Gorobay said. But if you’re not using similar values for anything else, and don’t want to mess around with something that wordy, you could just make it a general variable:

Friendship is a number that varies. Friendship is 25. Max friendship is a number that varies. Max friendship is 100.
And a little note about that ‘usually’: ‘usually’ is really only useful for kinds. (‘A chair is a kind of supporter. The weight of a chair is usually 15.’) What ‘usually’ does not do is allow a value to vary: that’s always allowed, ‘usually’ or not. For individual items, ‘usually’ doesn’t do anything.