Answer: The control height of the water in the tube prior to lowering is “x” then after lowering rock into the graduated cylinder the new height of the water is “y”. Due to the water being displaced and the mass of the rock the water will rises. Given the information from both the control and the data from “y” you want to subtract it from “x” (control) this will give the height at which it moved when the water was displaced by the rock. Hope this helped :)