Answer:
3 boxes of fertilisers.
Solving steps:
<u>Part A</u>:
Area of the garden, rectangle:
Length * Width
12 * 7
84 m²
Area of patio:
m²
Area of grass:
Area of the garden - Area of patio
84 m² - 9 m²
75 m²
<u>Part B</u>:
32 m² ↔ 1 box
1 m² ↔ box
75 m² ↔ boxes
75 m² ↔ 2.34375 boxes
- As she cannot buy exact 2.34375 boxes.
She should buy 3 boxes of fertilisers.