I am a 30 years old person who is planning on retirement at age 67. I expect to die with dignity at age 90 (I already have contract to die at this point) and leave nothing to anyone. My definition of retirement with dignity is to be able to support myself financially without support from anyone (family) or any entity (government/social security/pension). I am seeking your advice for retirement planning; how much should I save each month and how much should I have when I retire at age 67. I currently earn $72K/year and I can save as needed for my retirement, and I would like to maintain the same standard of living and spend the equivalent of $72K/year during my retirement. Assume an inflation rate of 3% per year and 7% average rate of return until age 67 and 3% after age 67. Please make the necessary assumptions to answer the above questions explaining the time value of money.

Answer in Excel for Engineering Economics, thanks.