The value of x is 16
Congruent triangles are triangles with equal corresponding angles and equal corresponding sides.
If ∆ ABC is congruent to ∆DEC, then the following angles are equal
angle A = angle D
angle B = angle E
angle C = angle C
angle B = x + 15
angle E = 6x -65
therefore;
x + 15 = 6x - 65
collect like terms
x - 6x = -65 -15
-5x = -80
divide both sides by -5
x = -80/-5
x = 16
Therefore, the value of x is 16