Hi:
You will need to create a new dataset -- either with a DATA step program or PROC SQL in which you create a new variable which is the result of the multiplication. Then you can plot the new variable and VariableA using either PROC GPLOT or PROC SGPLOT. There are lots of plotting examples in the documentation. For more information about how to create a new variable from an existing variables in an existing dataset, you should look at some of the examples in the documentation on Manipulating Data or using PROC SQL.
cynthia