The values in the table represent a linear function. What is the common difference of the associated arithmetic sequence?
х
1
2
у
8
23
38
53
68
3
4
5
A. 21
O B. 7
C. 15
O D. 1

Asource of laser light sends rays ab and ac toward two opposite walls of a hall. the light rays strike the walls at points b and c, as shown below: what is the distance between the walls?