Please answer correctly !!!!!!!!!!!! Will mark brainliest !!!!!!!!!!!!!!!!!!

Answer:
x = 7
Step-by-step explanation:
All the angles in a triangle added together equals 180 so:
64 + 71 + 9x - 18 = 180
add like terms
9x + 135 - 18 = 180
9x + 117 = 180
subtract 117 from both sides
9x = 63
divide by 9
x = 7
Answer:
x=7
Step-by-step explanation:
A triangle equals 180 and 64+71 is 135. 180-135 is 45. 9x-18=45.