Question

Lomov: I'll prove to you that they are mine.
Chubukov: You won't prove it.
Lomov: I shall. (Change into direct to indirect speech) ​

Answer 1

Answer:

Lomov said to chubukov that he will prove to him that they are his. Chubukov replied that he won't prove it. Then Lomov said he will.

Answer 2

Answer:

1.Lomov said he would prove to Natalya that they were his