Hey there! I'm happy to help!
We want to figure out what x is. To do this, we want to find all of the interior angles of this triangle.
We see that we have an angle measure of 66 degrees. It is right next to the missing angle of the triangle. Since they are both on a straight line, the sum of these angles is 180. Let's call this mystery angle a and see what it is.
6x+a=180
Subtract 6x from both sides.
a=180-6x
Now we have all of our triangle angles.
All of the interior angles of a triangle equal 180 degrees. We can now make this equation and solve for x.
180-6x+77+2x+3=180
We combine like terms.
260-4x=180
We subtract 260 from both sides.
-4x=-80
We divide both sides by 4
x=20
Now we look at angle s and plug in our x value to find its measure.
2(20)+3
40+3
43
The measure of angle s is 43 degrees.
Have a wonderful day! :D