hi there i am a little confused on how to answer these questions, any help would be great thanks!

1. You can afford to invest $150 per month in an annuity that earns 4% per year, compounded monthly. How long will it take before your investment is worth $6000 ?
2. You invested your summer earnings into an annuity from which you can draw expenses while you are at university. If you need to withdraw $1200each month for 9months of university, how much do you need to invest in an account, earning 6% per year, compounded semi-annually, in order to cover your expenses?
3. If $25000is invested into an account paying 4.5%per year, compounded quarterly, how much money can be withdrawn from the account every two months for the next 6 years?