If you begin investing at age 45 instead of age 40, how much more do you need to invest per month to have $retirement ? Why this amount so much greater than the difference between 20 and 25?

Ineed your ! i was to turn this into pond first thing i gotta do is outline the inside with this plastic how big should i cut the plastic the height: 10 1/2” the length: 40” the width: 12” me !