Answer:
B= 90
C= 80
D= 100
Step-by-step explanation:
So let’s start with the bottom angles.
We know that the adjacent angles in a parallelogram add up to 180° so our equation would be 
. So let’s simplify it b and b are both the same variables so we will get 2b and -10 + 10 is 0 so we get the following equation 
.
So now we divide 180 and 2 and we get 90 as b.
So one side will be 100 because of the +10 and the other 90 because of the -10.
Now for the next side.
So we know that b+10 is adjacent to c so 180-100 is 80, so 80 is c.
Now for d.
b-10 is 80 so 180-80 is 100, so d is 100.
Problem 7: Correct
Problem 8: Correct
Problem 9: Correct
The steps are below if you are curious
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Problem 7
S = 180*(n-2)
2340 = 180*(n-2)
2340/180 = n-2
13 = n-2
n-2 = 13
n = 13+2
n = 15
I'm using n in place of lowercase s, but the idea is the same. If anything, it is better to use n for the number of sides since S already stands for the sum of the interior angles. I'm not sure why your teacher decided to swap things like that.
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Problem 8
First find y
y+116 = 180
y+116-116 = 180-116
y = 64
which is then used to find x. The quadrilateral angles add up to 180*(n-2) = 180*(4-2) = 360 degrees
Add up the 4 angles, set the sum equal to 360, solve for x
x+y+125+72 = 360
x+64+125+72 = 360 ... substitution (plug in y = 64)
x+261 = 360
x+261-261 = 360-261
x = 99
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Problem 9
With any polygon, the sum of the exterior angles is always 360 degrees
The first two exterior angles add to 264. The missing exterior angle is x
x+264 = 360
x+264-264 = 360-264
x = 96
Let the three consecutive integers be x , x+1 ,x+2
Given, sum of three consecutive integers = -126
x +x+1+ x+2 = -126
3x +3 = -126
3x = -126 -3
3x = -129
x = -129/3
x = - 43
x +1 = -42
x +2 = -41
Answer:
Step-by-step explanation:
c
