suppose you own a bicycle but haven't found the time to ride it much lately. these days, it is only worth $40 to you. one of your close friends, who recently got a job at the college bookstore two miles down the road, wants to take it off your hands. he offers you $70 for the bicycle, and you gladly accept. your friend is also happy because he thinks the bicycle is worth $99 . how much total value was created from this trade? $ 30