Step 1: Let’s buy at least 1 of each type of fruit:
Total cost for 1 of each = ₹5 + ₹4 + ₹10 = ₹19.
Remaining amount = ₹100 - ₹19 = ₹81.
Step 2: Maximize the number of fruits with the remaining ₹81. The cheapest fruit is the mango (₹4).
Number of additional mangoes we can buy with ₹81: 81 ÷ 4 = 20 mangoes.
Total fruits = 1 apple + 1 mango + 1 watermelon + 20 mangoes = 23 fruits.
