A simple question needs a simple answer what they want if i am correct is the estimated payout of the quinella....this is the easiest way i know of and is pretty accurate
multiple the first horses win price x the second horses win price then devide by 2

as an example i went to a randome race
saturday sandown race 4
results
6 SARAH MICHELLE 7.00 unitab
1 DON'T TELL EM 4.20

7.00x4.20=29.40/2=14.70
the quinella paid 17.50

i know this is a little higher than what was estimated but unless you have all quinella prices of payouts in front of you this is the only way i know
this will work for exactas but the difference is you don't devide the result by 2 unless you have included the fav to win they always pay less.
One last interesting fact if you do this calculation for all the runners to find out what each pair will pay if comes out to about 118% market....like the win portion...i thought that was interesting