21.
a. Ratio of blue: green
Length blue: length green
3:6 or 1:2
Width blue :width green
2:4 or 1:2
Perimeter blue: perimeter green
2+2+3+3=10: 4+4+6+6= 20 or 1 :2
Area blue: Area green
2•3=6 : 4•6= 24 or 1:4
b. The lenght, with and perimeter of the big green rectangle are double the size of the small blue rectangle.
The area of the big green rectangle is 4 times greater than the area of the small blue rectangle. So if the lenghts of a rectangle are doubled the perimeter is doubled and the area is 4 times biger than the area of the doubeled rectangle.