A fruit seller had some Oranges. He sells 80% Oranges and still has 720 Oranges. Originally, number of Oranges, he had:

Correct option is B

20% = 720 So, 100% = 720 × 5 = 3600 Oranges
Explanation of options: (a) ✘ 3240 corresponds to 80%, not the total. (b) ✔ 20% is 720 ⇒ total = 720 × 5 = 3600 (c) ✘ 5400 is a large overestimate. (d) ✘ 900 is only 25% of total — incorrect reverse mapping.