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.

Firstly, look at the given area of the rectangle. As this is 20cm², the length and width of the rectangle could be a combination of 20 and 1; 10 and 2 or 5 and 4. Any of thse options could be used to solved the problem, but for example using, 5 and 4: 

Multiply 5 and 4 respectively by the scale factor of 3. This given 15 and 12. Multiplying these two numbers together gives a new area of the enlarged rectangle of 180cm².