Step-by-step explanation:
step 1. what is the question? maybe the question is what is the value of x in the diagram. okay.
step 2. interior angles of a triangle add up to 180°
step 3. the 3 angles inside the triangle are 10x + 8, 13 + 5x, and (180 - 126)
step 4. (10x + 8) + (13 + 5x) + 54 = 180
step 5. 15x + 21 = 126
step 6. 15x = 105
step 7. x = 7.
