CMAT 2024 Shift 1 Solved Paper

A train travelling at $48\mathrm{km}∕\mathrm{h}$ completely crosses another train having half the length of first train and travelling in opposite direction at $42\mathrm{km}∕\mathrm{h}$ in 12 seconds. The train having speed $48\mathrm{km}∕\mathrm{h}$ also passes a railway platform in 45 seconds. What is the length of the platform?