two trains running in opposite directions cross a man standing on the platform in 20 seconds and 18 seconds respectively and they cross each other in 19 seconds . the ratio of their speeds is :
"let the speeds of the two trains be x m / sec and y m / sec respectively . then , length of the first train = 20 x meters , and length of the second train = 18 y meters . ( 20 x + 15 y ) / ( x + y ) = 19 = = > 20 x + 18 y = 19 x + 19 y = = > x = y = = > x / y = 1 / 1 answer : option a"
divide(subtract(20, 19), subtract(19, 18))