A train travelling at 48 kmph crosses another train, having half of 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 railway platform is:

• ক 400m ✅ সঠিক উত্তর
• খ 200m
• গ 300m
• ঘ 350m