Can anyone help me? ill give brainiest if its correct! Which value is MEAN of the data set?

A) 480
B) 485
C) 500
D) The MEAN cannot be determined from the available information.

Which of these equations, when solved, gives a different value of x than the other three? a9.1 = -0.2x + 10 b10 = 9.1 + 0.2x c10 – 0.2x = 9.1 d9.1 – 10 = 0.2x

Haruka hiked several kilometers in the morning. she hiked only 66 kilometers in the afternoon, which was 25% less than she had hiked in the morning. how many kilometers did haruka hike in all?

What is the axis of symmetry of the function f(x)=-(x+ 9)(x-21)