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

Isabelle is mixing red and blue paint to make purple paint she adds 3/10 of a fluid ounce of red to 12/25 of a fluid ounce of blue to make 1 1/30 fluid ounces of purple how many fluid ounces of red paint ounces of red paint will she need to make 3 fluid ounces of purple paint