Ashton made contributions to a roth ira over the course of 32 working years. his contributions averaged $2,400 annually. ashton was in the 28% tax bracket during his working years. the average annual rate of return on the account was 8%. upon retirement, ashton stopped working and making roth ira contributions. instead, he started living on withdrawals from the retirement account. at this point, ashton dropped into the 15% tax bracket. factoring in taxes, what is the effective value of ashton's roth ira at retirement? assume annual compounding