physics
posted by help .
Mary and John are on opposite sides of a seesaw. Mary has 3x the mass of John. If Mary is sitting at a distance of .5m from the fulcrum, how far must John site in order to keep it balanced.

John's mass = x kg,
Mary's mass = 3x kg,
3x * 0.5 = x * d,
Solve for d by dividing both sides by x:
d = 3 * 0.5 = 1.5 m.