One way of thinking about this is to think about equivalent fractions and percents. If I gave you all of something, you would get 100 percent. If four friends had to split something four ways, we would each get one fourth of it. One fourth would be 25%, whether we were splitting $4 or $1000. In the problem that you posted, two people are sharing something equally. What fraction will each of them get? What is that fraction as a percentage?