I have a list of clients in A1:A30
Then in

Column B Column C Column D
Client's Name #Hrs $/Hr
1 Client1 5 100
2 Client 2 2 200
3 Client 3 1 50
4 Client 1 3 200
5 Client 3 1 100

I need to multiply Column C and Column D to get the total for the row, for
the client and then sum the results, by client.

Could any one please give me a light on how to do this?
Thanks.