Just tried it in Lotus which is pretty much the same as excel. Worked ok there

Starting at Cell A1
A1 Team 1 odds = 1.50
A2 Team 2 odds = 1.85
A3 Team 3 odds = 2.00
A4 Team 4 odds = 1.45
A5 @SUM(A1*A2*A3*A4) = 8.05


A6 @SUM(100/A5) = 12.43

To check Tally

@SUM(A5*A6) = 100.00

Obviously rounding occurs as 8.05 * 12.43 = 100.0615 (there are ways and means around rounding but not much point really when you cant bet in cent percentages anyway.

Hope that helps