Calculate mathematical formula using C# in ASP.Net

Hi

for calculating a formula in asp classic I could use the following expression: execute("result = 5 *(3+6)/(5-2)")

I mean: in the database I have field in which I can insert a formula.

I will not insert complicated formula. for me it is already ok when I can calculate formula like this:

(1) Value = price * quantity

(2) or Summe functions: Total = A + B

(3) or addition, subtraction x +y+z  ord x -y -z

(4) or multiplication / divission:  A = b * C or A = b / C 

(5) or like on the top: x = (a+b) / (C -d)

I was quite suprised that in the new application asp.net the function "execute('result = (...)')" is not working anymore.

how I have to do it in ASP.Net?

thanks

Chris