A. give a specific example of a well-defined function from z to z that is one to one, but is not onto. fully explain why your answer fits this description. b. give a specific example of a well-defined function from z to n that is onto, but is not one to one. fully explain why your answer fits this description.

Annuity formula for depositing at the end of each period.
Future value, 
F=A*((1+i)^n-1)/i
A=deposit per period, $3000 
i=interest per period, 10%/2 = 5% = 0.05 per half year
n=number of periods = 12 years = 24 half-years

If the deposit is at the beginning of each period, then
we can use the above formula, with 25 periods, but skipping the final payment, i.e.
F=A*((1+i)^(n+1)-1)/i-A
=3000*((1+.1/2)^(24+1)-1)/(.1/2) - 3000
=143181.296 - 3000
=143181.30 -3000
=140181.30 (to the nearest cent)