A square garden of side 20 m is surrounded by a path of uniform width 1 m on the outside. The AREA of the path (only the path, not the garden) is:

Outer square (garden + path) has side 20 + 1 + 1 = 22 m. Outer area = 22² = 484 m². Inner area (garden alone) = 20² = 400 m². Area of path = outer − inner = 484 − 400 = 84 m². (Trick: thinking 'path is 1m wide × 20m × 4 sides = 80 m²' undercounts because it forgets the four corners of the path — each 1×1 = 1 m² — totalling 4 extra → 80 + 4 = 84 m². ✓)