Select column B. Use Format/Conditional Formatting. Change "Cell Value is" to
"Formula Is". Enter this formula (assumes B1 is the active cell):
=OR(AND(A1="Car1",B1<=10),AND(A1="Car2",B1<=20),AN D(A1="Car3",B1<=30))
then click the Format button, Patterns tab, select Red.
(Untested).
Bob Umlas
Excel MVP

"Dave" wrote:

I have a set of data:

A B
Car1 12
Car2 19
Car1 11
Car3 31
Car1 9
Car2 22

I need column B to flash up RED if Car1 is 10 or less, Car2 is 20 or
less and if Car3 is 30 or less. I have no idea where to even start on
the formulas.

If anyone can help it would be great.