fifty-fifty
adverb, adjective uk/ˌfɪf.tiˈfɪf.ti/ us/ˌfɪf.tiˈfɪf.ti/
各半（的），对半（的），平分（的）
(into) equal halves
They divided the prize fifty-fifty. 他们平分了奖金。
There's only a fifty-fifty chance that she'll survive the operation. 她能够熬过手术的可能性只有50%。