In the following sentences use pronouns in place of nouns wherever you
can. Ensure that it remains a meaningful sentence.

1) John gave John?s pen to James and James lent the pen to Jill to write
Jill?s copy with the pen.

2) Atul loved Sandeep?s sweater and asked Sandeep from where Sandeep
had bought the sweater.

3) Lata found Lata?s books torn by Lata?s brother.

Dear Student,
Usually, when after a noun is mentioned for the first time, to avoid repetitive usage of the noun, pronouns are used. 
Given below are the answers:
1. John gave his pen to James, and he lent it to Jill to write her copy with it. 
2. Atul loved Sandeep's sweater and asked him from(redundant) where he had bought it. 
3. Lata found her books torn by her brother. 
Regards