Hello student!
We are given two angles that are right next to each other and are formed off of a 180 degree angle. These two angles are known as supplementary angles which means that the two angles add up to 180 degrees. Using that information we can create an equation to help us find x.
We now have a functioning equation which we can use to determine x. The first step that we have is to combine like terms which means to add together numbers which the same variables. In this case 5x and 4x would add together and -18 and 45 would also add together.
Now we are down to the final steps which is just some algebra. The first step that we need to do is subtract 27 from both sides which will remove the excess numbers from the left side.
The second step that we will need to do is divide both sides by 9 which will help us isolate x and give us our final answer.
Therefore, our final answer is that x is equal to 17.