HELP ME ASAP pls find the x for the quadrilateral you put them all together the numbers

Answer: x= 7
Step-by-step explanation:
16x - 3 + 84 + 9x + 12 + 14x - 6 = 360 (Angles in a quadrilateral add up to 360 degrees)
39x + 87 = 360
39x = 273
x = 273/39
x = 7