Geometry

Question Analysis:
This question combines algebra with triangle congruence concepts, requiring students to solve for a variable using corresponding parts of congruent triangles.

Key Concept Explanation:
When two triangles are congruent, all corresponding sides are equal in length.
This property allows us to set up equations to solve for unknown variables.

Step-by-Step Solution:
Since △ABC ≅ △DEF, corresponding sides AB and DE are equal.
Set up the equation: 5x - 2 = 13
Solve for x:
Add 2 to both sides: 5x = 15
Divide by 5: x = 3

Common Mistakes:
Forgetting that congruence implies equal corresponding sides.
Making arithmetic e...