Suppose the spot ask exchange rate, Sa($|), is $1.90 = 1.00 and the spot bid exchange rate, Sb($|), is $1.89 = 1.00. If you were to buy $10,000,000 worth of British pounds and then sell them five minutes later, how much of your $10,000,000 would be "eaten" by the bid-ask spread?

I don't know how to calulate the right answer. Could you please help me?