Answer:
82.67% of the fertilizer will be used on the property.
Explanation:
Area of Plane Figures
The backyard described in the problem has two parts: One with a rectangular shape of 30 feet by 20 feet. The other with a triangular shape with a base of 24 feet and a height of 12 feet.
The area of a rectangle is calculated by:

And the area of a triangle is:

All the backyard will be covered by fertilizer coming from a container with a capacity of 900 square feet.
The total area of the backyard is the sum of the area of the rectangle Ar and the area of the triangle At as follows:


The total area of the backyard is:

To find the percentage of the container, we calculate:

82.67% of the fertilizer will be used on the property.