steve traveled the first 2 hours of his journey at 40 mph and the last 2 hours of his journey at 80 mph . what is his average speed of travel for the entire journey ?
"average speed = total distance / total time = ( 40 * 2 + 80 * 2 ) / ( 2 + 2 ) = 240 / 4 = 60 answer : c"
add(divide(add(multiply(80, 2), multiply(40, 2)), add(2, 2)), subtract(divide(const_100, 2), const_0_33))