In preparation for retirement, you invest ${A} at the end of each month for the next {B} years. Using these savings when you retire, for how long (in years) can you withdraw ${C} at the end of each month. Assume interest is {D}% compounded semi-annually throughout. In preparation for retirement, you invest ${A} at the end of each month for the next {B} years. Using these savings when you retire, for how long (in years) can you withdraw ${C} at the end of each month. Assume interest is {D}% compounded semi-annually throughout