Basically in this problem, we are looking for an equation to solve for h, which is the elevation of the helicopter. First, let's understand the problem. 1812 is the difference of the helicopter and the submarine meaning this is the result of elevation of the helicopter minus the elevation of the submarine. So we know right away that this is a subtraction problem. We also know that the elevation of the submarine is (-734). It's a negative number because the submarine is underwater. So the equation is h- (-734)= 1812.