## Simple Motion Problem I Cannot Figure Out

Hi everyone, I am new to these forums and thought this would be a good place to get some help.

I picked up a three dollar russian made math problem book at a local book sale. I am working on the questions it has in it and I came across the first problem on motion it has and I cant quite figure it out. This is high-school level stuff by the way so I would hope its easy for many here.

Problem:

The train left station A for station B. Having travelled 450 km, which constitues 75 percent of the distance between A and B, the train was stopped by a snow-drift. Half an hour later the track was cleared and the engine-driver, having increased the speed by 15 km per hour arrived at station B on time. Find the initial speed of the train.

I have tried to visualize the problem. This is what I have come up with.

The question has no total time and you have to find speed. So are there two unknowns to solve? And how do I do that in this problem? Or is there a different way to solve this? Thanks for any help.

 Let the required time be T If there would have been no problem due to snow then the train wud have reached the station B in time T Now find sepearate times for two part of motion arising dua to a break of 0.5 hr + the time for break equate it will T
 Mathematical Form $$\frac{D}{v}=\frac{3D}{4v}+\frac{D}{4(v+15)}+ 0.5$$

Recognitions: