Grid To Determine Interest Rates

I have a grid to determine interest rates. The are add ons to the rate that are dependent on two factors - the credit score and the Loan to Value percent or LTV, both of which are shown in terms of ranges (720-739, etc). See the screen shot below.

I have already written formulas for converting the score and LTV to the ranges as they appear on the sheet (ie, if you type in a score of 722, the formula converts it to the range of 720-739.

What I need to do is this - when the score and LTV are input and determine which set of add ons come into play, I need the sheet to take those add-ons, identified by an x next to it at the top of the page, and add them to the base interest rate, giving me the final rate. Again, see below to make this more clear.

I've thought of using VLookup, but I don' think that would be applicable here.

What's the best method, and can you give me an example of what a formula might look like?

Loan Level Pricing Adjustments

Base Rate 6.25 6.25

Credit Score 741 >740

LTV 60 740 Cash Out 0 0 0 0.25 0.375 0.375 n/a >740 Investment 1.5 1.5 1.5 2 2.5 2.5 n/a >740 2-unit 0.5 0.5 0.5 0.5 0.5 0.5 0.5 >740 3-4 unit 1 1 1 1 n/a n/a n/a

720-739 all -0.25 0 0 0 0 0 0 720-739 Cash Out 0 0.125 0.125 0.375 0.5 0.5 n/a 720-739 Investment 1.5 1.5 1.5 2 2.25 2.5 n/a 720-739 2-unit 0.5 0.5 0.5 0.5 0.5 0.5 0.5 720-739 3-4 unit 1 1 1 1 n/a n/a n/a