If the planes are parallel to one another then they will never intersect (assuming they are distinct planes as the question states).
Otherwise they will intersect along a single line.
Therefore the answer is NEVER - they can never intersect in a pair of lines.
To figure out your question, just divide 999,999 by 9.
999,999/9 = 111,111
If the second equation is y=-3x+4 then they would be parallel and I found that by turning the first equation into y=mx+b and you subtract x from both sides of the equation and get -3y=-x+15 and then you divide both sides of the equation by -3 to get the y by itself and that turns into y=1/3x-5 and since 1/3 is the reciprocal of -3 they are perpendicular.
284=2x+2(x+40)
284=4x+80
204=4x
51=x
dimensions 51 ft by 91ft
