• Seeta, Rajinder and Surinder are children of Mr. and Mrs. Aggarwal.
• Renu, Raja and Sunil are children of Mr and Mrs. Malhotra.
• Sunil and Seeta are a married couple and Ashok and Sanjay are their children.
• Geeta and Rakesh are children of Mr. and Mrs. Gupta.
• Geeta is married to Surinder and has three children named Rita, Sonu and Raju.
What is Sanjay's surname?
Step 1: Identify Sanjay's parents.
Sunil and Seeta are married; Sanjay is their child.
Step 2: Find the family surnames.
Sunil belongs to Mr. & Mrs. Malhotra (siblings: Renu, Raja, Sunil).
Seeta belongs to Mr. & Mrs. Aggarwal (siblings: Seeta, Rajinder, Surinder).
Step 3: Assign surname by family line.
Children Ashok and Sanjay take their father Sunil's surname \(\Rightarrow\) \(\boxed{\text{Malhotra}}\).