Canadian dollar and Hong Kong dollar are both circulating currencies, so it is cheaper to open foreign exchange business directly-firm offer;

If it is calculated manually, it means converting Canadian dollars into RMB first, and RMB CHY= CAD 300 * cash purchase price of Canadian dollars 629.62-100; Then buy Hong Kong dollars in RMB, HKD= RMB CHY* cash selling price 82.1;

You only gave the price of Canadian dollar bills. By default, you have cash in your hand, and the buying and selling prices of banks are all paid by banks.