condition formatting involving formula

[chiuinggum]

if cell is A1=100

how do i set a conditional formating for the following

1) if cell B1 value is greater than A1 by 20% fill blue
2) if cell B1 value is lower than A1 by 10% fill red
3) if cell B1 value is between condition (1) & (2) fill yellow

 

[AKphidelt]

Go to

Format---> Conditional Formatting

Then you have 3 criterias you can make... just play around with that. Like
you can put greater then A1*.2

 

[Barb Reinhardt]

THe conditional format on b1 would be

=B1>A1*1.2
=B1<A1*0.9

Set the default color to YELLOW