This is a challenge to Donald Trump to prove that he has nothing to hide about his business dealings by producing his tax returns. Simple as that.
Why is this important?
What is Donald Trump hiding? By refusing to release his tax returns as he bids to become the next president of the USA, he is flouting modern electoral conventions and ignoring the wishes of the American people. By this simple act, by releasing his tax returns to open inspection by experts and lay folk alike, he can easily allay any fears of underhandedness or dishonesty in his business dealings. This is a big, big issue in this election, and he has nothing to fear if he has, as he repeatedly states, nothing to hide.