Plz simplify:
subtract
8x - 8y +9

5x - 8y -z

a.)3x + z + 9

b.)3x - 16y - z + 9

c.)3x -z + 9 it says that this was not the wright

i hoped that : )

Ahiker stands at an unknown elevation before he ascends 2 miles up a mountain to an elevation of 9 miles. find the elevation of the hiker before his ascent.

Cody was 165cm tall on the first day of school this year, which was 10% taller than he was on the first day of school last year.

From the top of a tree a bird looks down on a field mouse at an angle of depression of 50°. if the field mouse is 40 meters from the base of the tree, find the vertical distance from the ground to the bird's eyes.