Answer:
10
Step-by-step explanation:
The red square means the two outside lines form a right angle which equals 90 degrees.
10x + 16 + 54 = 90
Simplify:
10x + 70 = 90
Subtract 70 from both sides
10x = 20
Divide both sides by 10:
X = 2
The answer is x = 2
