find avrg speed if a man travels at speed of 32 km / hr up and 48 km / hr dawn at an altitude of 230 m .
"avg speed = 2 * x * y / ( x + y ) = 2 * 32 * 48 ( 32 + 48 ) = 38.4 answer : c"
divide(multiply(multiply(const_2, 32), 48), add(32, 48))