# Chapter 2 - Section 2.4 - The Angles of a Triangle - Exercises - Page 97: 20

m$\angle$B=x

#### Work Step by Step

Angles 1 and 5 form a straight line so they are supplementary. m$\angle$1+m$\angle$5=180 2x+m$\angle$5=180 m$\angle$5=180-2x m$\angle$3+m$\angle$5+m$\angle$B=180 x+180-2x+m$\angle$B=180 m$\angle$B=x

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