Why does the mass of an object remain constant regardless of it's location

What is the missing reason in the proof? segment addition congruent segments theorem transitive property of equality subtraction property of equality?

First work with stencil one. use a combination of reflections, rotations, and translations to see whether stencil one will overlap with the original pattern. list the sequence of rigid transformations you used in your attempt, noting the type of transformation, the direction, the coordinates, and the displacement in

Which of the following points is a solution to the system of equations shown? y - x = -1 x + y = -5