Video Transcript
Calculate the area of the grey parts.
The diagram shows three rectangles. And the area of a rectangle can be calculated by multiplying the length by the width. We have one large rectangle measuring 18 centimetres by 11 centimetres. Inside this rectangle, we have two smaller rectangles, one measuring five centimetres by four centimetres and the other five centimetres by two centimetres. The area of the grey part can, therefore, be calculated by subtracting the area of the smaller rectangles from the area of the large rectangle. The area of the large rectangle can be calculated by multiplying 18 by 11. This is equal to 198, as 18 multiplied by 10 is 180. And adding 18 to this gives us 198.
We can, therefore, say that the area of the large rectangle is 198 square centimetres. The area of the first small rectangle can be calculated by multiplying five by four. This is equal to 20. The area of the second small rectangle can be calculated by multiplying five by two. This is equal to 10. Therefore, we need to subtract 20 and 10 from 198 to calculate the area of the grey parts. 198 minus 20 is 178. Subtracting another 10 gives us 168. We can, therefore, conclude that the area of the grey or shaded part in the diagram is 168 square centimetres.
