Exchange
Reciprocation
noun, する verb
Repay what someone lent you in response to them already lending YOU money, and the two of you will have exchanged money.
おうしゅう
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
両チームのファンからやじの応酬が続いた。
Both teams’ fans continued to exchange jeers.