Excel formula to calculate a conversion rate knowing a $USD amt and a $AUD amt

I have some historical data in a s/sheet that shows a $USD amt and an $AUD amt

What I need to do is to have a formula that calculates what the CONVERSION RATE was on the day when that historical transaction took place

Some real data I am using is:

$USD 51.20
$AUD 55.58

Looking at a table of historical rates this shows that on the 29th May 2014, the answer was 1.07480

BUT

I would like a formula to calculate actual conversion rate knowing the two amounts above

Any assistance greatly appreciated

Thanks & Regards,

BazzaBit

Hi Glenn,
Pretty straightforward really. My head must have been a bit fuzzy because the results didn't look right
but on review A1/A2 will give what 1$USD will buy in $AUD and the reverse
will give what 1$AUD will buy in $USD

Thanks for your quick response

Bazzabit

Request solved