Ground chuck sells for $1.75 a pound. How many pounds of ground round selling for $2.45 a pound should be mixed with 20 pounds of ground chuck to obtain a mixture that sells for $2.05 a pound?

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?