Answer:
area is length 12 x width 3 = 36 square cm
Step-by-step explanation:
Always reread the question to make sure you're answering the right question and using the correct units.
length is 4w, width is w
perimeter is two lengths + two widths: 2(4w) + 2w = 30cm
solve for w: 10w = 30
width = 3, and length is 12