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. Just be sure to take note of the shortened けつ in 決. It goes to けっ.
They’ve decided to turn the Kumaman manga into an anime!
This will be your final decision and it can't be changed later. Is that okay?
I’ll leave the decision of whether we’re going to attend your little sister’s wedding or my mother’s funeral to you.