Alan Burnie has just started work and has been wanting to buy a sleek powerboat for sometime. Rather than purchase and finance now, he plans to save every three months and increase the deposits by 3% per annum as he expects raises at least that large. How much must the first deposit be if the boat costs $25,000 today and he expects to earn 10% on the money over the next five years?

What formula should I use? please don't say geometric annuity... It should similar to a growing annuity formula