Explanation: two angles that form a Line always equal 180 degrees, so we start with the equation 180-u+47, which is the measure of the missing interior angle measure. All of the angles inside of a triangle also equal 180 degrees, so we can set up this equation to find U: u-18+u+(180-u+47)=180 We can start to simplify by first simplifying what’s inside the parenthesis: u-18+u+153-u=180 Then you solve the equation to get U=45 degrees