how many seconds will a train 100 meters long take to cross a bridge 150 meters long if the speed of the train is 42 kmph ?
"d = 100 + 150 = 250 s = 42 * 5 / 18 = 11.7 mps t = 250 / 11.7 = 21.4 sec answer : a"
divide(add(150, 100), multiply(42, const_0_2778))