How to make a hierarchical structure Class

hi friends ...

i'm intending to make an application with visual basic 6.0

the application will solve some design proplems of civil enineering like design a beam , columns

and also to make a workshop drawing through the program by programming AutoCAD

to make this i'll make a ActiveX.dll component

to collect some useful functions of math, registery and so on

i want to make a parent class named sceeda

inside the activeX.dll component

and other classes like Math , Design, and so on

my question is :
****************

ho to make a hierarchical structure fashion so i can call the math class from the main class Sceeda

in other words ...


what code i write inside the ActiveX.dll allowing me to call a function in the Math Class from sceeda Class like this :

Sceeda.Math.CalculateAverage

where :

Sceeda :
********
the main class in the ActiveX.dll and have no functions ( the class is nearely empty)

Math:
******
the class i wrote the function or procedure called CalculateAverage

how to make a relation between 2 classes

i don;t want to call the math class directly from my application like this :

Math.CalculateAverage


N.B :

i'dont want to make inheritence

but something like aggregation

any one help me please

so many thanks

urs maximas