Calculate pricing according to selections made

Hi all,

Some help with this will be greatly appreciated!!

I need to calculate a specific price according to selections made, I have the following:

Insulation (selection 1)(attached sheet : "System 1-3" cell B7)
-19mm
-25mm

Pipe Sizes (selection 2)(attached sheet : "Pricing" E12:V12 & E13:V13)
- 18 Sizes, each with 2 prices, one incl 19mm insulation and one incl 25mm insulation

I need to calculate total cost (attached sheet : "System 1-3" cell E12) which will be Length (D12) * Pipe Cost (Which will be determined by the 2 selections mentioned above)

Thank you