Replace variables with numbers

Hi, I've been using your application for a while now and I can say that it works very well!

Thank you for making a such well-design and useful app!

Could it be possible to replace a variable by a value?
Like I have an equation like this :
x+r=h
and I tell piCubed :
x=9
r=3
and it gives me
x+r=12

that would be awesome!