The distance between the lines x = 7 and x = -2 is equal to ________ units.
Find the value of x such that points (0, 3), (x, 9) and (12, 15) are collinear.
The distance between the origin and P (3,√5,2) is ___ units.
If the distance between points P (x, 2) and Q (3, 6) is 10 units, then x = ___ units.