What is the density of the stone?

[Nguyenfa.t]

Homework Statement

When a 50 N stone is attached to a spring scale and is
submerged in water, the spring scale reads 35 N. What is the density
of the stone?

Homework Equations

The Attempt at a Solution

I found that the buoyant force is 15 N but i don't know what to do after. Can someone please help me step by step. I need to know this for my final tomm and I am stressing out.

 

[Nguyenfa.t]

i know it becomes 1000(50)/ 15 but i don't know where the 1000 came from. can someone please help?

 

[Kurdt]

Now you know the buoyant force you also know the volume of the boulder is the same as the volume of displaced water. So you can work out its volume in terms of the density of the water. Next you just divide its mass by the volume to find its density.