A square lawn 28m on each side has four identical quarter-circular flower beds removed from its corners. Each quarter circle has radius 7m and is cut from inside the lawn. Using this information, answer the following.
a. (i) Find the area of the lawn after the removal of the four quarter circles.
b. (ii) The outer edge of the remaining lawn (including the curved parts) is to be fenced with nylon wire. Determine the total length of wire required, expressing any part of your answer involving π in its simplest form.
c. (iii) If the lawn is to be levelled with topsoil to a depth of 15cm, calculate the volume of soil needed in cubic metres.