Answer:
144 degrees
Explanation:
Linear pair angle must add up to 180 degrees. We don't know what the angle is, so the call the unknown angle Ѳ.
We know that the bigger angle is 4 times as big as the unknown angle, so it's equal to 4Ѳ.
Add up the two unknown angle: Ѳ+4Ѳ=180 , because we know they must add up to 180 since they are linear pair as defined above.
Solve for Ѳ.
Plug the solved value of Ѳ back into 4Ѳ to find out how big 4Ѳ is.