An woman sitting in a train which is travelling at 25 kmph observes that a goods train travelling in a opposite direction, takes 3 seconds to pass him. If the goods train is 140 m long, find its speed. Choices:
A) 141
B) 142
C) 143
D) 144
E) 145
Relative speed = (140/3)m/s = (140/3)*(18/5)= 
<gadget id="calculator">(140/3)*(18/5)</gadget>
<output>168</output>
168 kmph   speed of goods train= 168-25= 
<gadget id="calculator">168-25</gadget>
<output>143</output>
143 kmph   Answer is 143
<result>C</result>
An woman sitting in a train which is travelling at 25 kmph observes that a goods train travelling in a opposite direction, takes 3 seconds to pass him. If the goods train is 140 m long, find its speed.