Two trains having equal lengths, take 10 seconds and 15 seconds respectively to cross a post. If the length of each train is 120 meters, in what time (in seconds) will they cross each other when traveling in opposite direction?
Options:
A) 22
B) 38
C) 12
D) 99
E) 73
Explanation:   Speed of train 1 = = 12 m/sec   Speed of train 2 = = 8 m/sec   if they travel in opposite direction, relative speed = 12 + 8= 
<gadget id="calculator">12 + 8</gadget>
<output>20</output>
20 m/sec   distance covered= 120 + 120= 
<gadget id="calculator">120 + 120</gadget>
<output>240</output>
240 m   time= distance/speed = 240/20= 
<gadget id="calculator">240/20</gadget>
<output>12</output>
12 sec   Answer: 12) 12
<result>C</result>
Two trains having equal lengths, take 10 seconds and 15 seconds respectively to cross a post. If the length of each train is 120 meters, in what time (in seconds) will they cross each other when traveling in opposite direction?