Is my military retirement annuity/pay taxed at the same rate as regular income, or is there a special tax rates for annuities?

I am trying to figure out if an annnuity would be my best bet when I retire.

What nominal rate compounded semi-annually is $8,000, the present value of $400 annuity payable semi-annually for 15 years. Please Show the Formula used (step by step process) and the interest rate.

You just won the state lottery. the state gives yo the choice of $1 million today or a 20 year annuity of $75,000 starting one yer from today (assume both are after taxes). what rate of return is built into he annuity equation usd? equation used?