Question 1091996
<br>In the 4 hours that the first train travels before the second train starts, the first train travels 4*50 = 200 miles.<br>
The second train travels 40mph faster than the first train (90 minus 50).<br>
The number of hours the second train needs to overtake the first train is the number of hours it needs to make up 200 miles, when it does so at a rate of 40 miles each hour:
{{{200/40 = 5}}}<br>
It takes the second train 5 hours to overtake the first.