After 20 people arrive, the unit has all:
50 + 20 = 70 (people)
70 people are 50 times as many:
70: 50 = 7/5 (times)
70 people eat that rice in the number of days are:
10 x 7/5 = 14 (day) (corresponding to 14 rice grades)
The additional rice capacity is:
14 - 10 = 4 (productivity)
Answer: 4 rates

After 20 people arrive, the unit has all:
50 + 20 = 70 (people)
70 people are 50 times as many:
70: 50 = 7/5 (times)
70 people eat that rice in the number of days are:
10 x 7/5 = 14 (day) (corresponding to 14 rice grades)
The additional rice capacity is:
14 - 10 = 4 (productivity)
Answer: 4 rates

After 20 people arrive, the unit has all:
50 + 20 = 70 (people)
70 people are 50 times as many:
70: 50 = 7/5 (times)
70 people eat that rice in the number of days are:
10 x 7/5 = 14 (day) (corresponding to 14 rice grades)
The additional rice capacity is:
14 - 10 = 4 (productivity)
Answer: 4 rates

\(\text{After 20 people arrive, the unit has all:}\) \(\text{ 50 + 20 = 70 (people)
}\)

70 people are 50 times as many:
70: 50 = 7/5 (times)
70 people eat that rice in the number of days are:
10 x 7/5 = 14 (day) (corresponding to 14 rice grades)
The additional rice capacity is:
14 - 10 = 4 (productivity) \(\text{Answer: 4 rates}\)