Question

1. ∠gfh≅∠ghf
2. given

2.

1. definition of congruent angles

3.

1. given (diagram)

4.

1. definition of linear pair
2. m∠efg + m∠gfh = 180°
3. definition of supplementary angles

6.

1. substitution property of equality
2. ∠efg and ∠ghf are supplementary.
3. definition of supplementary angles

Explanation:

Step1: Recall congruent - angles definition

If $\angle GFH\cong\angle GHF$, then $m\angle GFH = m\angle GHF$.

Step2: No information for step 3 given in problem - assume relevant angle - related given from diagram

No specific content provided for step 3, but it's a given from the diagram.

Step3: Recall linear - pair definition

Let's assume there are two adjacent angles forming a linear - pair, say $\angle EFG$ and another angle related to the previous ones.

Step4: Use substitution

Since $m\angle GFH = m\angle GHF$ (from step 1) and $m\angle EFG + m\angle GFH=180^{\circ}$ (from step 5), we substitute $m\angle GHF$ for $m\angle GFH$ to get $m\angle EFG + m\angle GHF = 180^{\circ}$.

Answer:

1. $m\angle GFH = m\angle GHF$
2. (No specific answer as no content given for what is given in the diagram)
3. (Assume relevant linear - pair description based on context)
4. $m\angle EFG + m\angle GHF = 180^{\circ}$