Explanation:
I assume you need the slope-intercept form
y = ax + b
"a" being the slope, "b" being the y-intercept (the y value when x = 0).
since we have the slope and a point, we can start with the point-slope form
y - y1 = a(x - x1)
"a" is again the slope, (x1, y1) is a point on the line
so, we have
y - -7 = 3(x - -4)
y + 7 = 3(x + 4) = 3x + 12
and from there now the final equation :
y = 3x + 5