Main Answer:
The angle measure that should equal 105° to prove

Therefore, the correct answer is b) 6°.
Explanation:
To demonstrate that
is equal to 105°, we need to consider the supplementary angles formed by the given angle measures. The sum of angles that form a straight line is 180°. If we let the unknown angle be
then the relationship between the angles can be expressed as:
![\[ a + b + c + d + n = 180^\circ \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/iihbr3fiv9pvvplhudexv2n0kofwiaj88l.png)
Since we are interested in
being equal to 105°, we can infer that
is equivalent to:
![\[ (n)/(180^\circ - n) \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/8hnzdytszc9q6lw8eoyl905e4oqj364efl.png)
The given options are
and
To find the correct value of \(n\), we set up the equation:
![\[ 6° / (180^\circ - 6°) = 105^\circ \]](https://img.qammunity.org/2024/formulas/mathematics/high-school/gfifmb286yzd4hvyxiw7d50rccjggwxdzn.png)
Solving this equation, we find that
is indeed 6°, making option (b) the correct choice. Therefore, option (b) 6° is the angle measure that should equal 105° to prove

Therefore, the correct answer is b) 6°.