Question

Can abs(28-7w)=7abs(w)
be written as abs(w-4)=abs(w)
and if so why surely it should be
abs(4-w)=abs(w)
can any one explain why I can just chane the signs


Yes, it can be written that way.

I don't see that you have changed any signs, you factored a postive seven out of both sides, and divided it out.

Thanks