YOU SAID:
hi my last name is your mom's last name
INTO JAPANESE
こんにちは私の姓はあなたのお母さんの姓です
BACK INTO ENGLISH
Hello my last name is your mother's last name
INTO JAPANESE
こんにちは私の姓はあなたのお母さんの姓です
BACK INTO ENGLISH
Hello my last name is your mother's last name
That didn't even make that much sense in English.