Answer:
B. 9°
Step-by-step explanation:
The given figure is an isosceles trapezoid.
Isosceles trapezoid means the non parallel sides must be equal.
In a trapezoid adjacent angles add upto 180 degrees. We are going to use this property to solve this problem.
In order to make the isosceles trapezoid to the rectangle, the top angles must be 90 degrees.
Given: (7x + 4) and 9x are adjacent angles that are add upto 180 degrees.
So, 7x + 4 + 9x = 180
Simplify the above equation, we get
16x + 4 = 180
16x = 180 - 4
16x = 176
Dividing both sides by 16, we get
x = 176/18
x = 11
Now let's find the each angle measures by plugging in x = 11
7x + 4 = 7(11) + 4 = 77 + 4 = 81 degrees
9x = 9x11 = 99 degrees
We are asked how many degree larger do the angles in the lower left and lower right corner should adjusted
In the lower left, we need to 9 degrees
81 + 9 = 90
In the lower right, we have to subtract 9 degrees.
99 - 9 = 90
So the answer is B. 9°
