It's the formula. Base times height. For example: if 50 is the base and 10 is the height, just multiply them both. 50 x 10 = 500. And I don't think you add area-that's for finding the perimeter
Step-by-step explanation: The question tells us that the population decreases by 1/4 every single year. That means, since 1/4 equals .25, the population decreases by 25% every year :)
