Answer:
Triangle DEF is congruent to triangle GHI.
Explanation:
There are theorems of congruency. They are SSS, SAS, ASA, and AAS. You can look these up if you are willing to master identifying similarity and congruency in triangles. It is an ideal concept. You can tell based off of marks of eqaulity which triangles are truly congruent. Just remember these theorems dela with angles and sides being eqaul.
(Khan academy is sure to help you master this. They have practice aswell)