Answer:
x = 144
Step-by-step explanation:
Sum of all angles of n-sided polygon = 180 * (n - 2)
Sum of all angles of 8-sided polygon = 180 * 6 = 1080
x + 129 + 132 + 136 + 124 + 141 + 158 + 116 = 1080
x + 936 = 1080
x = 1080 - 936
x = 144
Given the following question:
Point A = (7, 4) = (x1, y1)
Point B = (3, 6) = (x2, y2)
To find the slope use rise over run:

m = -0.5
Volume is area of the triangle multiplied by length:
area = 1/2*base*height
= 1/2*7*2
=7
therefore V = 7*18
= 126
Use point slope form or slope int to create an equation that meets the requirements

point slope form

slope int form