Answer:
#5
x = 45
E
Explanation:
Theorems you need:
- The measures of 2 adjacent angles that form a straight line with the outer sides add up to 180°.
- The sum of the interior angles of a triangle add up to 180° ((n-2)×180).
#5
Knowing those, you first want to find the triangle's 3 interior angles.
The angles <QSO & <QSR are adjacent (share a common ray) and form a straight line with the outer rays, therefore they add up to 180.
So m<QSO+m<QSR=180.
Rewrite the equation: m<QSR=180-m<QSO
Plug the known value in: m<QSR=180-(3x-17)
Distribution & Combining like terms: m<QSR=180-3x+17=197-3x
Now solve for the 3 interior angles to equal 180.
(197-3x)+(25)+(2x+3)=180
Combine like terms: 225-x=180
Isolate the x term (-225 to both sides): -x=180-225=-45
Isolate the x (×-1 to both sides):
x=45