Answer:
[tex]x = 40 \: \: degrees[/tex]
Step-by-step explanation:
[tex]3x + 20 + x = 180 \\ 4x + 20 = 180 \\ 4x = 180 - 20 \\ 4x = 160 \\ \frac{4x}{4} = \frac{160}{4} \\ x = 40 \: \: degrees[/tex]
