Answer:
b= -18
Explanation:
See attached image.
Formulate the equation for the line by calculation the slope and adding the y-intercept, as shown. The y-intercept if the value of y when x = 0. The equation of a straight line is y=mx+b, where m is the slope and b is the y-intercept. Note that this b is not the same b in the question (8,b). The b in the question may be calculated once the equation is found: y = -3x+6, where -3 is the slope and 6 is the y-intercept (0,6).
Use x = 8 in this equation. y = -3(8)+6, y = -18
The point is (8,-18), so b is -18.