In this problem, we have a balanced seesaw with a body of mass 60 kg placed on one end. We need to find the magnitude of the weight W.

To solve this problem, we need to understand the concept of torque. Torque is the rotational force that causes an object to rotate. The torque on an object is equal to the product of the force applied and the perpendicular distance from the point of rotation.

In this case, the seesaw is balanced, which means that the torque on one side of the seesaw is equal to the torque on the other side. The torque due to the weight W is equal to the torque due to the weight of the body.

Since the seesaw is balanced, the torque on both sides can be calculated as follows:

Torque on the left side = weight of the body * distance from point A to the left end

Torque on the right side = W * distance from point A to the right end

Since the seesaw is balanced, the torque on both sides should be equal. Therefore, we can set up the equation:

weight of the body * distance from point A to the left end = W * distance from point A to the right end

Plugging in the given values, we have:

60 kg