You are 30 years old now. You realise that a retired person nowadays needs a yearly $50 000 income, and the inflation rate will average 2% per year. You want to save enough money by the time you retire at 60 to have that income kept up with inflation from retirement forever. You will save in annual instalments, growing at a 5% rate. You plan to invest your saving, earning 10% per year after tax. Create a model to calculate how many dollars will you have invested at retirement and how much money you will have to save in the first year. Make all of these input variables so that a user can use the model for different realistic given values.