as a result, economists must compare real wages to dermine how the ability of workers to buy changes. 그 결과경제학자들은 근로자들의 구매력의 변화를 결정하기 위해 실질 임금을 비교해야한다.
여기서.. to buy 가 어떻게 쓰인건지 모르겠네요...

참고로 원문 올립니다.
wages are the main source of ① income for most people in the world. wages may be classified as money wages and real wages. money wages are the ② actual amount of money a worker receives from his or her boss. real wages represent the amount of goods and services workers can buy with their money wages. the prices of goods and services may change sharply over time. as a result, economists must compare ③ real wages to determine how the ability of workers to buy changes. that’s because such comparisons can ④ adjust according to changing prices. the growth of real wages over time is much more important than the growth of money wages because real-wage levels determine the purchasing power of ⑤ employers.