Please I need to know all formula used

You just started your first job. You want to start saving so that you can be ready for marriage in four years. To determine how much you should save, you calculate the following monthly expenses for the first 3 years of marriage. You expect these expenses to grow at a rate of 0.25% per month and you can earn interest of 1% per month at the bank. $600 in food, cleaning, staff, and household-related expenses $150 for car payments $500 for rent $400 for travel, shopping and leisure a. What is the total amount you need saved at the start of your marriage (i.e. at t=4) to cover the expenses of the first 3 years of marriage? b. How much do you have to save per month, starting at the end of the month, in order to make sure you have the total amount right before you get married? B li