A question with a phrase “how adjective” (how fast, how big, how tall) can be translated with “look like”.

How fast are you? = You fast look like?
How big are they? = They big look like?
How long is their hair? = Their hair long look like?

Note: The phrase “how old” doesn’t apply to this grammar.
Make sure to include eyebrow structure when asking a “how adjective” question.

examples
How tall is your house? 
How big is their boat?
How fast do you run?