You are given the area of the garden (960 m2) and the dimensions of the school that the garden is in (1 km by 800 m).
To find the total area excluding the garden, we first need to calculate the area of the school that the garden is in. Once we have that, subtracting the area of the garden from the total area of the school gives us the area without the garden.
Area of school = (1 km) · (800 m)
==> Before we go any further, the units of the dimensions have to be the same. Convert the measurement given in kilometers (km) into meters (m). Since there are 1000 meters in 1 kilometer, multiply 1 km by 1000m/1km:
(1 km)·(1000 m/1 km) = (1 km·1000 m)/(1 km) = 1000 m
Area of school = (1 km)·(800 m)
= (1000 m)·(800 m)
= 800,000 m2
Total area excluding the garden = Area of school - Area of garden
= 800,000 m2 - 960 m2
= 799,040 m2