The elevator went up 7 floors, making the current integer +7. The elevator then went down 4 floors, so 7 - 4 is 3. The final answer representing the change in floor level is +3 (positive three.)
1) Vertical angles-the angles will equal each other. 8+7x=9x-4 12+7x=9x 12=2x x=6 2) Supplementary-Angles will add up to 180 6+13x+7x+14=180 20+20x=180 20x=160 x=8