Pawan's speed downstream = 24 + 4.8 = 28.8 km/h
Pawan's speed upstream = 24 - 4.8 = 19.2 km/h
Let the required distance be x.
According to the question.
x/28.8 + x/19.2 = 1
⇒ (19.2x + 28.8x) / 552.96 = 1
⇒ 19.2x + 28.8x = 552.96
⇒ 48x = 552.96
∴ x = 552.96/48 = 11.52 km