Calculating annual sales increase

Hi Everyone,

I am trying to find a formula that i can use on an entire column to input the sales increase in Column T.

This figure needs to pull from the value in Column O minus the value Column F associated with the correct client.

As an example I have done this manually using the formula =SUM(O4-F4) for the client A2, however i need a formula that will do this automatically for all entries in column S (in the actual spreadsheet there are around 160 which will take too long manually) it needs to look for the client name in both columns B and K, then return the difference between the two in Column T, which as mentioned above will be the value of the figure in Column O minus the value of the figure in Column F.

I hope this makes sense to someone, i am struggling to figure out which type of formula to use?

Thanks in advance EXCEL Problem.xlsx

Thanks John, that has worked a treat. Very much appreciated