In this case, we'll have to carry out several steps to find the solution.
Step 01:
Data:
x y
4 1
5 2
6 3
7 4
y = x - ?
Step 02:
equation of the line:
y = x - ?
y = mx + b
m = slope = 1
point ( 4 , 1)
Point-slope form of the line
(y - y1) = m (x - x1)
(y - 1) = 1 (x - 4)
y - 1 = x - 4
y = x - 4 + 1
y = x - 3
The answer is:
y = x - 3