Points Q, R, S, and T are plotted on the number line. RST -2-11 -1 - 01 1 1 2 a. Which two plotted points have a sum of zero? b. Explain how the number line can be used to show that the sum of the two points you identified is zero. c. Explain how the number line can be used to determine the sum of the location of point T and -11