Find the number of degrees in an angle which is 0.2 times a straight line angle.

Concept: A straight line angle is the angle formed by two rays pointing in exactly opposite directions along a straight line, and it always measures 180 degrees.

1. Straight line angle = 180 degrees.

2. The required angle is 0.2 times this straight line angle.

3. Required angle = 0.2 × 180 degrees = 36 degrees.

Cross-check: 0.2 is equivalent to the fraction 1/5, and one-fifth of 180 degrees is 180 ÷ 5 = 36 degrees, confirming the result by a second method.