The weight of a glass of jar is 20% of the weight of the jar filled with coffee beans. After some of the beans have been removed, the weight of the jar and the remaining beans is 60% of the original total weight. What fraction part of the beans remain in the jar? Choose one:
A) 1 / 5  B) 1 / 3  C) 2 / 5  D) 1 / 2  E) 2 / 3

Rationale: "let weight of jar filled with beans = 100 g weight of jar = 20 g weight of coffee beans = 80 g weight of jar and remaining beans = 60 g weight of remaining beans = 40 g fraction remaining = 40 / 80 = 1 / 2 answer is d ."
Answer: D