Step 1: Since x = 60°, triangle ABC is an equilateral triangle with sides all equal.

The sides are all equal to 8.

Perimeter of triangle ABC = 8 + 8 + 8 = 24.

Step 2 : Triangle DEF has two angles equal, so it must be an isosceles triangle.

The two equal sides will be opposite the equal angles.

So, the length of DF = length of DE = 10.

Perimeter of triangle DEF = 10 + 10 + 4 = 24.

Step 3: Subtract the two perimeters.

24 – 24 = 0