Add multiple if statements in one cell?

Registration date
Friday September 26, 2014
Last seen
September 26, 2014
Here is my current formula:

what that does is only gives me the result of one of the "KM" calculations. If one or all of R2,t2,v2,x2 contain "KM" I would like to return the total of the calculations. In other words add the 4 calculations together if applicable. If only one contained "KM" then fine, but if two or more contained "KM" I would like the result to be the x+x+x+x (x being the total of the calc in each IF statement. Make sense?