Если бы ты помог своей младшей сест

Если бы ты помог своей младшей сестре с домашним заданием,она не получила бы плохую отметку.

Результаты (английский) 1:

If you had helped his younger sister with homework, she would have not a bad mark.

Результаты (английский) 2:

If you helped her younger sister with homework, she would not have received a bad mark.

Результаты (английский) 3:

if you helped his sister with her homework, she wouldn't get a black mark.