Explanation:
We wish to express 3x - y = 1
in slope-intercept form.
3x - y = 1
=> y = 3x - 1
Slope of line = 3, therefore
Slope of parallel line is also 3.
We have y = 3x + c.
When x = 1, y = 7.
=> (7) = 3(1) + c, c = 4
Hence the answer is y = 3x + 4.