Question 423416
I'm not really sure how to read this, but I
think what they mean is:
  Out of the 30 years I have before retirement,
I want to earn $60,000/yr for 20 of those
years. So, for the first 10 years I would 
reinvest all the money and on the 11th year,
I would draw out exactly $20,000, and keep
drawing the same amount out for 20 years.
To find the minimum I must start with, I've
got to assume that ,on the 30th year, I will
exhaust all my investment.
  So, the 1st part of the equation is {{{P}}} dollars
initial investment + reinvested principle and
interest over 10 years.
Let {{{A}}} = amount after 10 years
{{{ A = P*(1 + 10*.05) }}} (simple interest formula)
So, after 10 years I must have {{{20*60000 = 1200000}}}
{{{ 1200000 = P*1.5 }}}
{{{ P = 1200000/1.5 }}}
{{{ P = 800000 }}}
I need to invest $800,000 today.
I hope either or both the explanation and solution are helpful.