To analyze the system of equations given:
- First Equation: \( y = -3x + 7 \)
- Second Equation: \( y = -3x - 7 \)
Both equations have the same slope of \(-3\), but they have different y-intercepts (7 for the first equation and -7 for the second equation). Because they have the same slope but different y-intercepts, the lines are parallel and will never intersect.
Thus, the correct statement from the choices provided is:
Both equations have a slope of -3, but they do not share the same y-intercept. Thus, the system has no solutions because the lines are parallel.