First divide the parts where it is a rectangle and semicircle.
Find the area of the rectangle:
A = length × breadth
A = 18m × 16m
A = 288m²
Then find the area of the semi-circle. We know that the area of a circle is πr² and half that area gives you the area of a semi-circle: πr²/2
A = πr²/2
A = π(6)²/2
A = 18πm² or 56.549m²
Total Area = 288m² + 18πm²
OR
288m² + 56.549m² = 344.549m²
Hope it helps!