20 days to finish it alone. NowРJia firstly makes it alone for 5 days, then the rest of the project is made alone by team Yi. How many days?more are needed to finish the project?Р18. As the following shown, here is a parallelogram (平行四边形 )ABCD. If the areas of triangle PAB andРPCD are 37c㎡, 7c㎡, what is the area of parallelogram ABCD?Р.Р19. T here are 3 consecutive natural numbers which are all less than 2005, the minimum of t hem can be divided?by 13, the mi ddle one of them can be di vi ded by 15, and the largest can be divided by 17.?Q: Whi ch is the l argest number of these three numbers?Р20. The steps on each floor(from up to down) consi（st 构成） of alternate（交替）black and white square tilesРas shown. If this pattern continues, How many tiles are there on the 20th floor?Р南外冲刺群 284066211
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