Explanation:
So now a full triangle is 180°
Since the full triangle is 180°..you have to minus it with 68°and 70°.
![180 - 68 - 70 = 42](https://img.qammunity.org/2021/formulas/mathematics/high-school/nkcgpx6cljz83iconfybfi131da2ejqvs1.png)
This is what you will get
Now write the value (42). Now you have the degree for a whole triangle
Since they are asking you to find the outside angle, you have to minus 42 with 180. This because that's a half circle
Full circle=360
Half circle =180
![180 - 42 = 138](https://img.qammunity.org/2021/formulas/mathematics/high-school/k1q4yh7e7118jsbyjtqrxx4g52n0esfa81.png)
Hope this is correct and helpful
HAVE A GOOD DAY!