a 400 meter long train crosses a platform in 45 seconds while it crosses a signal pole in 30 seconds . what is the length of the platform ?
"speed = [ 400 / 30 ] m / sec = 40 / 3 m / sec . let the length of the platform be x meters . then , x + 400 / 45 = 40 / 3 3 ( x + 400 ) = 1800 è x = 200 m . answer : a"
subtract(multiply(divide(400, 30), 45), 400)