I have problems with understanding how to operate with proportionality the first problem is with a question above.
Say we have two relations A proportional to B and C is proportional to D then if we divide the two relations why do we get A upon C is equals to B upon D and not A/C = KB/QD k and q being some numbers
Another question is why can a term be substituted in one relation from another for example:-
a is proportional to p a + (n-1)x is proportional to q Then why is p + (n-1)x proportional to q
Also, Why can we substitute relations in equations
I don't seem to understand how proportionality works if there are any other rules for applications that I've missed can you also please tell me those?