So I have a little question, which is probably very simple, but it's been over 15 years since I studied any Maths...
So, I am working through a question and I have to subtract one equation from another to get my answer. I have to subtract S=0.1M + 18660 from S=5M - 174200. How and why do I know to do S=(5M - 0.1M) - (174200 +18660)? I mean why would I not do '0.1M - 5M'?