there are 28 stations between ernakulam and chennai. how many second class tickets have to be printed, so that a passenger can travel from one station to any other station?	Choose the correct answer.
A) 800
B) 820
C) 850
D) 870
E) 900
<gadget id="calculator">28 + 2</gadget>
<output>30</output>

<gadget id="calculator">30 - 1</gadget>
<output>29</output>

<gadget id="calculator">30 * 29</gadget>
<output>870</output>

<result>D</result>
there are 28 stations between ernakulam and chennai. how many second class tickets have to be printed, so that a passenger can travel from one station to any other station?
multiply(add(28, const_2), subtract(add(28, const_2), const_1))
"the total number of stations = 30 from 30 stations we have to choose any two stations and the direction of travel ( ernakulam to chennai is different from chennai to ernakulam ) in 30 p 2 ways . 30 p 2 = 30 * 29 = 870 answer : d"