Since the smaller rectangle is a 1/2 scale drawing of the original figure, you may either multiply the measurements of the original figure by 1/2 or divide the measurements of the original figure by 2. Then, to find the area, multiply the length times the width.
Length: 36/2 = 18 cm Width: 28/2 = 14 cm Area: 18 * 14 = 252 cm²