What is the mean of this data set? 11,12,16,11,15,19,13

Some boys and girls were asked if they had a pet. one third of the group were boys. there were 20 boys. 20% of the girls had a pet. boys with a pet : girls with a pet = 1 : 5 i need to know how many girls there are.

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

Cos^2x+cos^2(120°+x)+cos^2(120°-x)i need this asap. pls me