- A10
- B25
- C5
- D20
Step-by-Step Solution
A card from Asha to Bina differs from one from Bina to Asha, so order counts: . (10 would count each pair once, as for handshakes.)
Answer: D) 20
On Diwali, each of 5 friends sends one greeting card to every other friend in the group. How many cards are sent in all?
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