a train consists of 12 boggies , each boggy 15 metres long . the train crosses a telegraph post in 9 seconds . due to some problem , three boggies were detached . the train now crosses a telegraph post in
"length of train = 12 ã — 15 = 180 m . then , speed of train = 180 â  „ 9 = 20 m / s now , length of train = 9 ã — 15 = 135 m â ˆ ´ required time = 135 â  „ 20 = 6.75 sec . answer a"
divide(subtract(multiply(12, 15), 15), divide(multiply(12, 15), 9))