In a parallelogram the 4 angles need to sum to 360 degrees. There are two sets of identical angles, so one of the other angles would also be 80 degrees.
Now find the other two angles:
360 - 80 - 80 = 200 degrees
200 degrees / 21 = 100 degrees each.
The other 3 angles are: 80, 100 and 100
Answer: C
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The answer is a is greater than or equal to 13 :)
1.) 4 - t = 3(t - 1) - 5
4 - t = 3t - 3 - 5
4 - t = 3t - 8
3t + t = 4 + 8
4t = 12
t = 12/4 = 3
2.) 8x - 2(x + 1) = 2(3x - 1)
8x - 2x - 2 = 6x - 2
6x - 2 = 6x - 2
0 = 0
solution is identity.
3.) 3(c - 2) = 2(c - 6)
3c - 6 = 2c - 12
3c - 2c = -12 + 6
c = -6
4.) 0.5(m + 4) = 3(m - 1)
0.5m + 2 = 3m - 3
3m - 0.5m = 2 + 3
2.5m = 5
m = 5/2.5 = 2
m = 2
As we know that the area of a rectangle is -
length × Breadth
So, here length = (3n+1)
Breadth = (2n-5)
Area of rectangle
= (3n+1)(2n-5)
= 3n(2n-5)+1(2n-5)
= 6n² - 15n + 2n - 5
= 6n² - 13n - 5
Answer) Area of rectangle is 6n² - 13n - 5