John Camey, the money manager of the First State Bank, has estimated that the bank has a 20 percent chance of a liquidity deficit of $700 million, a 30 percent chance of a liquidity deficit of $200 million, a 30 percent chance of a liquidity surplus of $400 million and a 20 percent chance of a liquidity surplus of $900 million over the next week. What is the bank's expected liquidity deficit or surplus over the next week? A. $100 million liquidity surplus B. $100 million liquidity deficit C. $400 million liquidity surplus D. $500 million liquidity surplus E. $0 liquidity surplus

how is the answer A how do we solve it?