Given:
The measures of the alternate exterior angles are (180 - x)° and x°
We need to determine the value x that makes m ║ n
Value of x:
We know that the measures of alternate exterior angles are equal.
Thus, we have;
![180-x=x](https://img.qammunity.org/2021/formulas/mathematics/high-school/aqc9aa82vuc7ffr03y30kkxa3h4i39z15m.png)
Adding both sides of the equation by x, we have;
![180-x+x=x+x](https://img.qammunity.org/2021/formulas/mathematics/high-school/glmybiqbwlgzcj8avbldvj5qto3g5gsvfm.png)
Simplifying, we get;
![180=2x](https://img.qammunity.org/2021/formulas/mathematics/high-school/8fap4az6bfngwalyqy554ixvndoh69gany.png)
Dividing both sides of the equation by 2, we have;
![90=x](https://img.qammunity.org/2021/formulas/mathematics/high-school/yq5g98a6w5ktb0x58ojgqcdobjobycsh60.png)
Thus, the value of x is 90.
Hence, the value x = 90 makes the alternate exterior angles congruent and hence the line m is parallel to n.