The perimeter of a rectangle is given by the formula:
length+length+breadth+breadth= perimeter
So, you have to substitute the values in using the question ( breadth plus breadth becomes 2b)
9+9+2b=24
18+2b=24
Take 18 to the other side as a negative number
2b= 6
Divide both sides by 2
Therefore, the breadth is 3cm
The area of rectangle is given by the formula:
length*width=area
Using the breadth, the area is 9*3, which is 27cm^2