单选题 A bank has $100 million in assets in the 0 percent risk-weight category, $500 million in assets in the 20 percent risk-weight category, $800 million in assets in the 50 percent risk-weight category, $500 million in assets in the 100 percent risk-weight category. This bank has $15 million in common stock, $ 20 million in capital surplus, $ 35 million in subordinated bonds, $15 million in undivided profits. What is this bank's ratio of Tier 1 capital to risk-weighted assets