Answer: Area of the rectangular board is 1.08 square meters
The length of the rectangular board = 1200 milimeters
The width of the rectangular board = 900 milimeters
Area of a rectangle = Length x width
Firstly, we need to convert the milimeter to meters
1000mm = 1m
1200mm = xm
Cross multiply
x * 1000 = 1200 x 1
1000x = 1200
Divide both sides by 1000
x = 1200/100
x = 1.2 meters
For the width
1000mm = 1m
900mm = xm
cross multiply
1000 * x = 900 * 1
1000x = 900
Divide both sides by 1000
x = 900/1000
x = 0.9m
Length = 1.2 meters
Width = 0.9 meter
Area = length x width
Area = 1.2 x 0.9
Area = 1.08 square meters