each rectangle has the opp sides equal...in your case let one be x and the other y
then what is the perimeter.....it is 2x+2y and it is 23 cm this is one equation.
then what is the area of this rectangle? it is xy and it is equal to 33 cs square.
if you understand all these then the only thing remaining is to solve the system of simultaneous equations
to find the dimensions of the rectangle..solve it to find x=6 and y=11/2