Select cell E3, then click on conditional formatting | Manage Rules and choose the rule that gives rise to the purple colour and click on Edit Rule. Now choose Use a Formula... from the bottom of the list and enter this formula in the formula box:

=AND(E3=$E$25,$A2="x")

then click OK twice to exit the dialogue box. Excel will automatically adjust the cell references to suit the other cells in the range.

Hope this helps.

Pete