YOU SAID:

the hamburgers was eaten on the dishes by clients, and then they was washed

INTO JAPANESE

ハンバーガーは客が皿の上で食べてから洗った

BACK INTO ENGLISH

The hamburger was washed after the customer had eaten it on the plate.

INTO JAPANESE

ハンバーガーは客が皿の上で食べた後、洗われた。

BACK INTO ENGLISH

The hamburger was washed after the customer had eaten it on the plate.