Answer:
Option B is correct.
the measure of angle HGI is 21°
Explanation:
By Angle bisector definition:
A line that bisects the angle into equal angle
From the given figure, we have;
and
![\angle HGI = (3x-9)^(\circ)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/g7nvrubihs7f3tmose9widhgdt12b3yzl9.png)
it is given that: GH bisects ∠FGI.
then by definition:
![\angle FGH = \angle HGI](https://img.qammunity.org/2020/formulas/mathematics/middle-school/340tnrppfq1turxsxv3oua2mi15rdnr5ru.png)
Substitute the given values we have;
![2x+1 = 3x -9](https://img.qammunity.org/2020/formulas/mathematics/middle-school/3y2qbv07oss01sa2hplxwn7hpryegia3dp.png)
Add 9 to both sides we get;
![2x+10= 3x](https://img.qammunity.org/2020/formulas/mathematics/middle-school/rygqhf75v8n26br95bu6ruunzdtl77hqu7.png)
Subtract 2x from both sides we get;
![10= x](https://img.qammunity.org/2020/formulas/mathematics/middle-school/8v08c3pbvt856ffjshdl1tted8t124wdsx.png)
or
![x= 10](https://img.qammunity.org/2020/formulas/mathematics/middle-school/47uoz3bz296q0wl4i4hi129pivz75pcm2x.png)
then;
![\angle HGI = 3x-9 = 3(10)-9 = 30-9 = 21^(\circ)](https://img.qammunity.org/2020/formulas/mathematics/middle-school/3vjk3y6ykxxx8g4obr9j23ejfphi2pc29b.png)
Therefore, the measure of angle HGI is 21°