Windows XP Pro SP3
Excel 2007

Suppose cells A1:A10 contain integer values. Now suppose cells B1:B10
also contain integer values. I'd like to conditionally format the
values in column B so that if the value in column B is greater than
100% of the value in column A then the B cell is shaded red. If the
value in column B is greater than or equal to 75% but less than 100%
of the value in column A then the B cell is shaded yellow. If the
value in column B is less than 75% of the value in column A then the B
cell is shaded green. Is this possible?

A B
=============
20 18 <-- shaded yellow
50 10 <-- shaded green
75 81 <-- shaded red