If the length and width of a rectangle are doubled what happens to the area

4 times the previous area

The area is multiplied by 4.

For example: If the length and width is 5 and 10, the area is equal to 50. If the length and width double to 10 and 20, the area is equal to 200. 200 is 4 times 50, so the area has been multiplied by 4.