Ted went to a nursery where grass beds were sold. In order to put them on his lawn, he bought 28 rectangular grass beds measuring 10 cm by 15 cm. When he went back and arranged the grass beds on his lawn, 4 beds were left unused. Find the area of the lawn (in square cm).
The area of each grass bed = 10 cm × 15 cm = 150 cm2
Number of grass beds that were bought = 28
Number of grass beds Ted used = 28-4 = 24 grass beds
(Since 4 beds were left unused)
Thus, the area of the lawn
= 24 × area of each grass bed
= 24 × 150 = 3600 cm2