A positive + A positive = A positive (1+2=3)
A negative + A negative = A negative (-1+(-2)=-3)
Adding a negative is like subtracting a positive (1 + (-2) = -1) this is equal to (1 - 2 = -1)
Adding a positive is like subtracting a negative (-1 + 2 = 1)
For number one, the answer will be C because the ratio between the side and the perimeter of the Pentagon will be 1/5 or 2/10 or 3/15. For number 2, we know that the Pentagon had 5 sides, and the side of it is 8, so the perimeter of this Pentagon will be 8+8+8+8+8 or 40 inches, which is C. Hope it help!
15. 70° because a right angle is 90° and we have the angle of ADB which is 20°. So 90°-20°=70°.
16. 70° because angle PSQ is 60° and angle QSR is 10°. So 60°+10°=70°.
17. 55° because it says it in the explanation. I assume this is a typo and they meant to ask the measurement of ADC and in that case it would be 130° because angle ADB is 75° and angle BDC is 55°. 75°+55°=130°.
18. 40° because angle PSQ is a right angle which means it's 90°. So 130°-90°=40°.
19. 140° because angle ADB is 120° and angle BDC is 20° so 120°+20°=140°.
20. 125° because again it's in the explanation. But if it's a typo and they meant what is the measurement of PSQ then it is 50° because PSR is 125° and QSR is 75° so 125°-75°=50°.
Hope this helps! :)
