The internal angle sum of a quadrilateral is :
C. 360°
The sum of internal angles of a polygon is determined by a formula :

where n represents number of sides.
In a quadrilateral there are four sides,
So, plugging 4 in the formula :
_____________________________

2/10 as a percent would be 20%.
Answer:
It's a polygon
Step-by-step explanation:
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Answer:
C. (3,2)
Step-by-step explanation:
to begin the substitution method, we can begin by substituting the answer choice value into the given system or equations to determine if the values make the equation true.
the first choice is (2,1)
3(2) + 2(1) = 13
6 + 2 is not equal to 13. Therefore this answer choice is incorrect.
second choice (1,2)
3(1) + 2(2) = 13
3 + 4 is not equal to 13. This answer is also incorrect.
third choice (3,2)
3(3) + 2(2)
9 + 4 = 13 is true!
we can also substitute these x and y values for the equation underneath:
y = x - 1
2 = 3 - 1
2 = 2 is true! Therefore, C. (3,2) is correct!