Answer:
x = -10
Step-by-step explanation:
The interior angles of a triangle adds up to 180 degrees
⇒ 180 = 90 + 29 + (71 + x)
add like terms:
⇒ 90 + 29 + 71= 190
⇒ 180 = 190 + x
subtract 190 from each side
⇒ 180 - 190 = 190 - 190 + x
⇒ -10 = x
answer: x = -10
