Originally Posted by

**J Rahman**
Hey, this is getting on my nerves. I have been thinking over this very fundamental thing of Mathematics for quite a long time without finding any possible solution. Here it goes.

Say, 'a' is proportional to 'b', and 'a' is again proportional to 'c', then we may infer a conclusion from this that 'a' is proportional to 'bc'.

Fine! This is true indeed. Every now and then we use this conclusion in Physics. So what I want now is a mathematical proof of this assertion, which I have been trying to find with no success at all. Please help.