Does anyone knows how to do that?
I need to solve for x

Answer:
[tex]x=17[/tex]°
Step-by-step explanation:
Because the diagonal lines are marked with arrows, we know that they are parallel. The two angles that are marked with measures are same-side interior angles. Same-side interior angles of parallel lines are supplementary, meaning that the sum of their measures is [tex]180[/tex]°.
Now, with all of this information, we can set up the following equation and solve for [tex]x[/tex]:
[tex]115+4x-3=180[/tex]
[tex]112+4x=180[/tex] (Simplify LHS by combining like terms)
[tex]112+4x-112=180-112[/tex] (Subtract [tex]112[/tex] from both sides of the equation to isolate [tex]x[/tex])
[tex]4x=68[/tex] (Simplify)
[tex]\frac{4x}{4}=\frac{68}{4}[/tex] (Divide both sides of the equation by [tex]4[/tex] to get rid of [tex]x[/tex]'s coefficient)
[tex]x=17[/tex]° (Simplify)
Hope this helps!