Can someone help me figure the question out it’s geometry btw!! Please and thank you!

What is the image of c for a 90° counterclockwise rotation about a? (3, 7) (-1, 3) (7, 3)

9is the geometric mean between x and 12

Ahousekeeper mixed 5 gallons of blue paint with every 9 gallon of yellow paint in order to make a green paint which ratio of gallon of blue paint to gallon of yellow paint will make the same shade of green paint