First we need to find the value of x. Since angles 3 and 6 are equal to 180 (by the Same-Side Angle Theorem) we can set them equal to 180 to find x.
(8x-13)+(4x+1)=180
Simplified is
12x-12=180
Add 12 to both side to get
12x=192
Divide by 12 to get that x=16
Now we can plug this into angle 6 to find its measure.
8(16)-13=?
128-13=115
Then to get angle 7, we subtract this from 180.
180-115=65
So angle 7 is equal to 65 degrees.
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