Answer:
y = -3x + 3

Step-by-step explanation:
Slope of a line passing through two points (
) and
is determined by the formula,
Slope = 
If these points are (0, 3) and (3, -6),
Slope of the line passing through these lines =
= (-3)
Equation of the line which passes through (0, 3) and slope = (-3),
y - y' = m(x - x')
y - 3 = (-3)(x- 0)
y - 3 = -3x
y = -3x + 3
Now slope of another line that passes through (3, -6) and (0, -7),
m' = 
m' = 
Equation of the line that passes through (0, -7) and slope = 
y - (-7) = 
y + 7 = 
y = 
Therefore, system of linear equations are,
y = -3x + 3