A line parallel to y = 4x + 4 has slope 4 too — that part is free. These free printable worksheets give a point and a line in slope-intercept form and ask for the line through the point that runs alongside it, which means finding a new y-intercept.
If they get stuck
The answer key prints on a separate page.
The slope is copied and the intercept is not, and the second half is the whole exercise. Through (−2, −7) parallel to y = 4x + 4: m = 4, then b = −7 − (4)(−2) = 1, so the line is y = 4x + 1. The key writes those three lines for every question. The given line's intercept is never the answer's, so writing the given line out again is never right — a parallel line through a point off the given line cannot share its intercept.
Finding b is a signed substitution, and the signs are where it goes wrong. Every point sits off the y-axis, so the intercept always has to be worked out; slopes run from −4 to 4 and about a third of them are negative, so b = y − mx often subtracts a negative. Some answers come out with b = 0, as in y = 2x — a line through the origin, not a missing number.