<image>As shown in the image, the rectangular floor is paved with square tiles of the same specification. Please observe the following figures and answer the questions:
(1) In the nth figure, each row contains ____ tiles, and each column contains ____ tiles; (both expressed as algebraic expressions in terms of n)
(2) According to the paving scheme mentioned above, a total of 420 tiles are used to pave such a rectangular floor. How many tiles are used in each row in this case?
