A train travelling at 48 kmph completely crosses another train having half its length and travelling in opposite direction at 42 kmph, in 12 seconds. It also passes a railway platform in 45 seconds. The length of the platform is

• ক 450 m
• খ 400 m ✅ সঠিক উত্তর
• গ 560 m
• ঘ 600 m