A rectangle has an area of 20 cm2. Its length and width are enlarged by scale factor 3. Find the area of the enlarged rectangle.

Area of rectangle is 20 cm². The new area of the enlarged rectangle is the original area, 20 cm², times the area scale factor. We are only given the length scale factor, therefore, we need to work out the area scale factor. The area scale factor is the length scale factor times itself, in other words lsf x lsf. The length scale factor (lsf)is 3, substituting in the numbers, the area scale factor is 3 x 3, or 3² , =9.
The new area = original area x area scale factor
The new area = 20 x 9
The new area = 180 cm² (don't forget the units)