A=18cm2 thats in the in side of the rectangle. the out side says 6cm and it says what is the base

Okay so a rectangle has 4 sides, and they have 2 equal sides. So the outside is 6cm, so another side must be 6cm. 18-12=4, and 4 divided by 2 is 2. So the base is 2. You can check this by adding all the sides together, and this should equal 18. So 6+6+2+2=18

The base is easy to solve for. To solve for it divide 18 by 6 to get the other side length. Other length=3