If the line is parallel to y=-7x+3, it must have the same slope, that is: -7.
Hence, your line equation is:
y = -7 x + n
To calculate the intercept use the fact that the line passes through the point (-6,-2). If you substitute the coordinates of the point in the equation, the equation should hold (if the point belongs to the line):
-2 = -7× (-6) + n
Solve in n:
-2 = 42 + n ⇒ n = -44
The equation is:
y = -7 x - 44
