Breakdown of Заказчик и исполнитель согласовали ставку.
Questions & Answers about Заказчик и исполнитель согласовали ставку.
Because the subject is actually two people/entities joined by и: заказчик и исполнитель.
In Russian, just like in English, a compound subject with and normally takes a plural verb:
- Заказчик согласовал ставку. = one person agreed the rate.
- Заказчик и исполнитель согласовали ставку. = two parties agreed the rate.
So согласовали is the past tense plural form.
They are in the nominative case, because they are the subject of the sentence.
You can tell because these are the basic dictionary forms:
- заказчик = client/customer who commissions work
- исполнитель = performer/executor/contractor
In this sentence, they are the ones doing the action of agreeing, so nominative is expected.