we know that
m ∠4+m ∠1=[tex]180\°[/tex] ------> by supplementary angles
Substitute the value of m ∠4 and find the measure of m ∠1
m ∠1=[tex]180\°-2x[/tex]
Remember that the sum of the internal angles of the triangle is equal to [tex]180\°[/tex]
so
m ∠1+m ∠2+m ∠3=[tex]180\°[/tex]
Substitute the values and solve for x
[tex]180\°-2x\°+(4/3)x\°+20\°=180\°[/tex]
[tex]2x\°-(4/3)x\°=20\°[/tex]
[tex](2/3)x\°=20\°[/tex]
[tex]x=30\°[/tex]
therefore
the answer is the option C
[tex]30\°[/tex]
