Tom, and Harry weigh 50, 85, and 120 lbs. respectively and use a 12 ft. plank for a teeterboard. Tom sits 5 ft. sits 4 ft. and Harry sits 3 ft. from the fulcrum on the same side. The fulcrum is at the midpoint of the board. How far must a 200-pound friend sit from the fulcrum to balance them?

When I read this problem, I thought it would be easy. But, I have done this over and over and can't get the right answer. :rolleyes:

You have two people listed, but three weights.?

Moment is distance times weight.

5(50)+4(85)+3(120)=200x

Solve for x.

That is how far from the fulcrum the friend should sit.