What is the solution to this system of linear equations? y − x = 6

y + x = −10

A. (−2, −8)
B. (−8, −2)
C. (6, −10)
D. (−10, 6)

Thank you if you can help me!

Grace is standing 18 feet from a lighthouse and kelly is standing 10 feet from grace. the angle that grace looks up to see the top of the lighthouse is 45°. the angle that kelly looks up to see the top of the lighthouse is y°. find the height, h, of the lighthouse. find the angle, rounded to the nearest tenth of a degree, in which kelly looks up to the top of the lighthouse. to the nearest tenth of a degree, find the value of x° . in two or more sentences, explain your calculations