Adjectives only end in a 't', if the noun is neuter-gender (if you use "et" in front of it)

En blå skjorte = a blue shirt En stor bil = a big car

Et blåt hus = a blue house Et stort bord = a big table

En sød pige med et sødt smil = a sweet girl with a sweet smile

Hope that helps :)

(this is only in singular, if it's plural you don't add 't' for neuter-gender nouns. "Et blåt hus" becomes "to blå huse")