Ineed don't understand this?

dg , eg , and fg are perpendicular bisectors of the sides of △abc . dg=5 cm and bd=12 cm.

what is cg ?

enter your answer in the box.

cm

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?