Respuesta :
The very first statement is true. No need to worry about the rest!
Try it out. If you have 9 cups and I have 6... and we both take 3 more... now you have 12 and I have 9. You still have more.
If I have 10 dollars in the bank and you have 5 and we both add -3 to our account by paying a monthly fee - I will have 7 and you will have 2. I have five more than you in both examples.
Adding the same amount to both sides does not change the solution.