The water level of a creek has risen 4 inches above its flood stage if it continues to rise steadily at 2 inches per hour how long will it take for the creek to be 12 inches above its flood stage

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?