Answer:
Bill got more ($1.62) for each pound exchanged than did Gwyll ($1.56).
Step-by-step explanation:
Let's calculate the unit rate in each case, that is, the number of dollars obtained through exchanging one (1) pound for dollars:
Bill:
$729
--------- = $1.62 per pound
£450
Gwyll:
$780
---------- = $1.56 per pound
£500
Bill got more ($1.62) for each pound exchanged than did Gwyll ($1.56).