Answer:
an = -50n + 600
Explanation:
Expand it
an = 550 - 50n + 50
an = 600 - 50n
This looks similar to the linear equation: y = mx + c
Rearrange an = 600 - 50n to match the form of a linear function
an = -50n + 600
Hence the function has a negative gradient of 50 and has a y-intercept at (0,600)