Final answer:
The banking system can increase its total demand deposits by $5 million.
Step-by-step explanation:
The banking system can increase its total demand deposits by $5 million.
The reserve ratio is the percentage of deposits that a bank is required to hold in reserve. In this case, the reserve ratio is 20%. If the bank has a change in reserves of $1 million, it can increase its total demand deposits by $5 million ($1 million divided by 0.2).