The price for a product increase with 2,00 euro when the size increase with 5 cm.
The minimum price is 6,00 euro for 15 cm, so 20 cm=8,00; 25 cm=10,00; 30 cm=12,00.
WA_eCart calculation : [Price]+(((([Size]-15)/5)*2))
Now I want the price increase with just 1,00 euro from size 35 cm, so that 35 cm=13 euro.
How do I have to make the calculation ?