Please help! I will mark your brainiest, thank you!

Answer:
6
Step-by-step explanation:
The straight line (at the bottom) measures a total of 180 degrees. So we can write an equation where the sum of all of the angles = 180:
180 = 5x + x + 54 + 90
90 comes from the square indicating a right angle.
Using that equation, solve for x.
180 = 5x + x + 54 + 90
First, combine like terms.
180 = 6x + 144
Then subtract 144 from both sides
36 = 6x
Divide both sides by 6 to isolate x
6 = x
So x = 6°