The measures of the angles of a triangle are shown in the figure below.
Solve for x.

The angles of a triangle should equal to 180 degrees. Here, we are given two full angles of 39 degrees and the right angle, 90 degrees. So, 39 and 90 are equal to 129 and to get to 180, we need 51 more degrees. This means that our equation that we have to solve for X should equal to 51 degrees. We can write our equation like this: 9x-3 = 51. To solve for X, we first need to get rid of 3 from our left side, so to get rid of 3 from our left side, we have to add 3 to both sides of our equation. This is our equation after this: 9x = 54. Lastly, to get X just by itself to solve for our answer, we have ego divide both sides by 9. So, our equation should end up like this: X = 6. So, X is equal to 6. You can plug it into the equation and then add all of the angles and they should equal to 180 degrees.