Official Business
Noun
こうよう
今、公用でパリにきています。
I’m coming to Paris now on official business.
これは公用のアカウントです。
This is an official account.
おれたちがぬすむのは公用のかねだ。
We’re gonna steal government money.
A public task is going to be government business. You have to think of this public as government to know the meaning of this word easily.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.