Two swimmers started simultaneously from the beach, one to the south and the other to the east. Two hours later the least distance between them is 100Km. Find the speed (km/hr) of the faster swimmer, knowing that the speed of the other is 75% of the one?

After 2 hours, swimmers form a right triangle with the starting point. Let faster swimmer's speed = v km/hr, then slower = 0.75v km/hr. Distances: faster travels 2v km, slower travels 1.5v km. By Pythagorean theorem: (2v)² + (1.5v)² = 100². This gives 4v² + 2.25v² = 10000, so 6.25v² = 10000, v² = 1600, v = 40 km/hr (faster swimmer's speed). The slower swimmer is 0.75 × 40 = 30 km/hr. Verification: √((80)² + (60)²) = √(6400+3600) = √10000 = 100 km ✓.