If the mean of the data set shown below is 11, find x. x, 12, 8, 15

11.5
10
9

Will gve pints stars and brainliest

I'm confused on this could anyone me and show me what i need to do to solve it.

On her first stroke, maya hit a golf ball 146 yards, 2 feet, 11 inches. on her second stroke, she hit it 163 yards, 1 foot, 2 inches. how far did the ball go all together? convert the answer to larger units whenever possible.