Answer: 72
Step-by-step explanation:
We know that the sum of all exterior angles of a polygon is 360°.
Therefore, by the given picture, we have
[tex](x+12)^{\circ}+57^{\circ}+108^{\circ}+60^{\circ}+51^{\circ}=360^{\circ}\\\\\Rightarrow x+288^{\circ}=360^{\circ}\\\\\Rightarrow\ x=360^{\circ}-288^{\circ}\\\\\Rightarrow\ x=72^{\circ}[/tex]
Hence, the value of [tex]=72[/tex]
