there are 18 stations between hyderabad and bangalore . how many second class tickets have to be printed , so that a passenger can travel from any station to any other station ?
"the total number of stations = 20 from 20 stations we have to choose any two stations and the direction of travel ( i . e . , hyderabad to bangalore is different from bangalore to hyderabad ) in ² ⁰ p ₂ ways . ² ⁰ p ₂ = 20 * 19 = 380 . answer : e"
multiply(add(18, const_1), add(add(18, const_1), const_1))