Answer: -2
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Work Shown:
m = 1 is the given slope
The point (x,y) = (4,2) is on the line
Use slope intercept form to find the y intercept
y = mx+b
2 = 1*4 + b
2 = 4 + b
2-4 = b
-2 = b
b = -2 is the y intercept