Long-term borrowing costs in the US eased on Wednesday after the Treasury department announced it would buy back more debt.The move came after the interest rate on 30-year bonds, which are a type of debt used to raise funds from investors, hit 5.34% on Tuesday - the highest level in almost 20 years.The high rates, known as yields, affect the rate the US government and major corporations can borrow money at, but also impact borrowing costs consumers pay on the likes of mortgages, car loans and credit cards.T ...