I am confused on what I need to do. someone please help?

Answer:
x = 16
Step-by-step explanation:
Since ∆ABC is congruent to ∆DEC, their corresponding angles would be equal to each other.
<B is congruent to <E, therefore,
<B = <E
x + 15 = 6x - 65 (substitution)
Collect like terms
x - 6x = -15 - 65
-5x = -80
Divide both sides by -5
x = 16