YOU SAID:

My mum said me that when I am going to be 18 years old she would give 1000$ and a beatiful big car

INTO JAPANESE

私の母は、私が18歳になると、1000ドルと美しい大きな車をくれると言っていました。

BACK INTO ENGLISH

My mother said that when I was 18, she would give me a beautiful big car for $ 1000.

INTO JAPANESE

母は、私が18歳のとき、美しい大きな車を1000ドルでくれると言っていました。

BACK INTO ENGLISH

My mother said that when I was 18, she would give me a beautiful big car for $ 1000.