The buoyant force of this object is 60 N. Buoyant force is a difficult concept to understand, so I’ll take the rest of this answer to explain what it is, and do my best to explain why the answer is 60 N. First off, the buoyant force is just the force of the water pushing up on the object. If your object is five inches long, the part at the bottom of that five inches is being pushed upwards more than the top is being pushed downwards.
According to Kahn Academy, the formula for buoyant force is simply the density of the fluid times gravity times how much fluid is displaced.
However, since we do not know how much gravity is pulling on the object in this problem, our answer is at most a guess, and at best, a crapshoot.