You have to distribute the 4 to the numbers in the parenthesese. So 4 times 3x which is 12x and 4 times 5 which is 20 so now you get 12x plus 20 equals 8. Now you have to subtract 20 from 8 which is -12 so now you have 12x=-12 now divide the 12 from x and 12 from -12 and so now you have x=-1
Answer:
7 of the angles measure 144 degrees each and one angle measures 72 degrees
Step-by-step explanation:
Let
x -----> represent the measures of the seven same-size angles,
x/2 ----> represent the measure of the one that is "two times smaller."
we know that
The sum of internal angles of a polygon can be calculated as:

where
n is the number of sides of the polygon
In this case
n=8 (octagon)
substitute

so
The linear equation that represent this problem is

solve for x

so

therefore
7 of the angles measure 144 degrees each and one angle measures 72 degrees
Answer:

Step-by-step explanation:
