Answer:
148º
Step-by-step explanation:
Use the information given:
- The measure of a straight line is 180º. So angle PST=180-(2R+8)
- Since ST and QR are parallel, angle PST=angle PQR. Now, angle PQR=180-(2R+8)
- The sum of a triangle's interior angles is 180º. So 40+180-2R-8+R=180º.
- Combine like terms, 212-R=180
- Subtract, -R=-32
- Convert to positive, R=32º
With R=32º, we can find angle QST and PQR. Angle QST=2(32)+8=64+8=72º. So angle PQR=180º-72º=108º. The sum of a quadrilateral's interior angles is 360º:
- 32º+72º+108º+STR=360º
- Combine like terms, 212º+STR=360º
- Subtract, STR=148º
