Answer:
86
Explanation:
First we need to know that a hexagon contains 540 degrees worth of angles.
Now we can build an equation:
x + 21 + 105 + x + 154 + 88 = 540
Now we gather like terms:
2x + 368 = 540
Subtract 368 from both sides of the equation:
2x + 368 -368 = 540 -368
2x = 172
Now we divide both sides by 2 to isolate the x:
![(x)/(2) = (172)/(2)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/xgd6qo905yzy67domje6trbx0r4tb9btgd.png)
x = 86