Answer:
Bill's exchange rate was $1 to £1.62
Gwyll's exchange rate was $1 to £1.56
Explanation:
Given
Bill changed £450 into $729
Gwyll changes £500 into $780
Required
Determine their exchange rates
Exchange rate is calculated by dividing the currencies against one another.
Given that they both changed from pound to dollar, the exchange rate is calculated as thus;

Calculating Bill's Exchange Rate


Represent as a ratio

Hence, Bill's exchange rate was $1 to £1.62
Calculating Gwyll's Exchange Rate, using the same formula and steps


Represent as a ratio

Hence, Gwyll's exchange rate was $1 to £1.56