Vectors - Lines and Planes Question

According to an astronomy club, Earth is a plane described by the equation

x + y + z = 18.

The club also stated that Earth will be destroyed by an explosion that will spontaneously occur at point A = (1, 1, 1). Note that point A is not a point on Earth, it is a point in space that will explode and will impact Earth.

a/ Calculate the co-ordinate of the first point that is going to be destroyed by this explosion.

b/ What is the distance between point A and the first point that is going to be destroyed (mentioned in a)? (Hint: Shortest Distance)