Question

click to correct the pronoun if needed. not only did nicolas - louis robert invent the first machine for producing paper in a continuous roll, but him and his brother also helped launch the first hydrogen balloon.

Explanation:

The pronoun "him" is in the objective - case, but here it should be in the subjective - case as it is part of the subject of the second clause. The correct form is "he".

Answer:

Not only did Nicolas - Louis Robert invent the first machine for producing paper in a continuous roll, but he and his brother also helped launch the first hydrogen balloon.