In a visual sequence of nested shapes, Step 1 consists of a heptagon (7 sides) inside an octagon (8 sides). Step 2 consists of a hexagon (6 sides) inside a nonagon (9 sides). Step 3 consists of a pentagon (5 sides) inside a decagon (10 sides). Following this dual progression of increasing outer sides and decreasing inner sides, what nested shapes will make up Step 5?