Question 709488
L=W+3
P=2L+2W
30=2(W+3)+2W
30=2W+6+2W
30-6=4W
24=4W
24/4=W 
6=W ANS.
L=6+3=9 ANS.
PROOF:
30=2*9+2*6
30=18+12
30=30
AREA=LW
AREA=6*9=54 cm^2 ANS.