The area of the garden to be covered in grass and the cost to put grass in the garden are;
(a) 78.25 m²
(b) £391.5
How the area of the garden to be covered in grass can be found; The area of the garden that will be covered by grass can be obtained from the difference between the rectangular area of the garden and the sum of the area of the patio and the sandpit
(a) The rectangular area of the garden is; 7 m × 15 m = 105 m²
The area of the parallelogram patio is; 5 m × 4 m = 20 m²
Area of the parallelogram shaped sandpit is; 1.5 m × 4.5 m = 6.75 m²
Area of the garden covered in grass is; 105 - (20 + 6.75) = 78.25 m²
(b) The area covered by a roll of grass = 3 m²
The cost of a roll of grass = £14.50
Number of rolls of grass requires to cover the garden is; 78.25/3 ≈ 26.1, rounding up to the next higher integer, the number of rolls of grass to cover the garden is about 27 rolls
The cost of the 27 rolls of grass to cover the garden is; 27 × £14.50 = £391.5