Calculating the Exchange Rate
exchange rate is the amount of money that is paid for a unit of foreign currency.
To calculate exchange rates;
If 1 CAD = 0.63 GBP therefore 1GBP = 1/0.63 = 1.59CAN and if 1CAD = 0.75 USD, then 1USD =1/0.75 = 1.33CAD$

To calculate exchange rates based on the Big Mac index it is

cost country A / cost country B = x / $1 country B

from that you simply cross multiply to find $x to $1 country B