The equation for line A is y= 1/3x+4. Suppose line A is parallel to line B and point (-3,1) lies on line B Y= -3x-8
Y=1/3x
Y=-3x+4
Y=1/3x+2

Parallel lines have same slope
y = 1/3x + 4, the slope is 1/3
Therefore y = 1/3x + b
Plug in the point (-3,1)
1 = 1/3(-3) + b
1 = -1 + b, b = 2
Solution: y = 1/3x + 2