How much did you deposit at the end of each month into an investment account that pays 5.5% compounded monthly to have 3 million when you retire in 43 years how much of them 3 million comes from the interest

Me its important ! marge runs an ice cream parlor. her speciality is triple chocolate sundaes.she can prepare 1 sundae every 2 minutes, and she earns $1.20 for each sundae she makes . if she just makes sundaes for a single shift of at most 4 hours and at least 2 hours , which function relates her earnings to the number of minutes she works?