How + adverb/adjective
To ask "to what degree?" we can use how+adverb/adjective. In Spanish the phrase may have to be reworded to include the noun with qué.
When it's an affirmitive sentence we can use lo+ adverb/adjective
E.g.
How fast is your new scooter? — ¿A qué velocidad puede ir tu moto nueva?
How good are you at golf? — ¿Cómo se te da el golf?
How hot was it? — ¿Cuánto calor hacía?
How wide is the road? — ¿Qué anchura tiene la carretera?
You don't understand how hard it is living with him — No entiendes lo difícil que es vivir con él