Answer:
y = -x + 7
Explanation:
y = x + 5 works for the first row, but fails for the rest.
y = x + 3 fails for the first row
y = -x + 7 works for the first row ( -1 + 7 = 6)
It works for the second row ( -2 + 7 = 5)
It works for the third row ( -3 + 7 = 4)
And it works for the final row ( -4 + 7 = 3)