x=10
Explanation
the sum of the internal angles in a triangle always equals 180,so
Step 1
[tex]\begin{gathered} 85+46+(9+4x)=180 \\ 131+9+4x=180 \\ 140+4x=180\rightarrow Equation(1) \end{gathered}[/tex]Step 2
solve the equation
[tex]\begin{gathered} 140+4x=180 \\ \text{subtract 140 in both sides} \\ 140+4x-140=180-140 \\ 4x=40 \\ \text{divide both sides by 4} \\ \frac{4x}{4}=\frac{40}{4} \\ x=10 \end{gathered}[/tex]Step 3
find the missin angle( yellow)
replace x=10
[tex]\begin{gathered} 9+4x \\ 9+4\cdot10 \\ 9+40 \\ 49 \end{gathered}[/tex]so, the yellow angle is 49 degrees
so, the answer is x=10,
I hope this helps you
