Answer:
Three planes.
Step-by-step explanation:
In 2 dimensional system we have only 2 unknowns and these 2 unknown can be solve by the intersection of two lines.
Ex:In 2-D ,equation of lines
x + 2y = 4
y-x= 8
These two lines will give point.
Similarly in 3 dimensional we have 3 unknowns and these 3 unknown can be solve by the intersection of three lines.
Ex:In 3-D,equation of planes
x+2y+Z=8
x + y+6z=12
2x+ y+z = 20