a train 130 m long crosses a platform with a speed of 70 kmph in 20 sec ; find the length of the platform ?
"d = 130 + x t = 20 s = 130 + x / 15 * 18 / 5 = 70 kmph . = > ( 130 + x ) * 18 = 5250 = > 130 + x = 292 = > x = 162 m answer : d"
subtract(multiply(20, multiply(70, const_0_2778)), 130)