I know the answer, but I'm not sure how to 'approach' the question the right way.
The question is
"Katarina would like to buy a house in 4.5 years time and requires a deposit of $40000. What contribution should she make every six months into an account earning interest of 6% p.a. compounded half-yearly to reach this amount?"
I have access to a future value of annuity table, but I don't think you need to use this.