Use original length and width of 100 each to compare areas.<br><br>&bull; Original: L = 100, W = 100, Area = 100 × 100 = 10000<br>&bull; New: L = 120, W = 80, Area = 120 × 80 = 9600<br>&bull; Change = 9600 − 10000 = −400<br>&bull; Percentage change = \(\frac{-400}{10000} \times 100\% = -4\%\)<br><br>Final Answer: 4% decrease