Linking Product values and units to Potential value

Linking Product values and units to Potential value

I am a new user.  My first challenge is that I want to create potentials that include a number of products.  This I can do but I want the value of the products to be linked to the overall potential value.

So I may have two Products

A = £10 x 2 units
B = £20 x 1 Unit

Total Value = £40  (I want to make this the total potential value)

Any help would be appreciated.

I have already set up products with a value in products...