V-Lookup/IF Statement Question! Help Please!

Hello All,

Having some trouble figuring out how to create a formula for my spreadsheet that I will show below.

See attached DOC

What I am trying to do is for
-COL C (Total Units) to only add Impressions ONLY IF the Rate Type (COL D) reads as "CPM"
-COL C (Total Units) to only add Clicks ONLY IF the Rate Type (COL D) reads as "CPC"

In the example above, I would not want COL C to include Impressions because it states "CPC" {Cost Per Click}

My first thought is to have a IF statement formula but I am not sure if that will work.

Help Please!