Answer:
To solve this problem, we can use the principle of moments. The principle of moments states that the sum of the moments on one side of a fulcrum is equal to the sum of the moments on the other side, when a system is in equilibrium.
In this case, we have two people, Steve and Billy, on opposite ends of a seesaw. We know that Steve weighs 120 pounds and is 9 feet from the fulcrum. We want to find out how much Billy weighs, given that he is 10 feet from the fulcrum.
Let's assume that the seesaw is balanced, which means that the sum of the moments on one side of the fulcrum is equal to the sum of the moments on the other side. We can set up an equation to represent this:
Moment of Steve = Moment of Billy
To calculate the moment of each person, we need to multiply their weight by their distance from the fulcrum. We can use pounds and feet as our units, which means that the moments will be in pound-feet (lb-ft). Using this information, we can write:
120 lb x 9 ft = Billy's weight x 10 ft
Simplifying this equation, we get:
1080 lb-ft = 10 ft x Billy's weight
Dividing both sides by 10 ft, we get:
Billy's weight = 1080 lb-ft / 10 ft = 108 pounds
Therefore, Billy weighs 108 pounds.