là cái bàn chải đánh răng

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de to cho nit trieu van voi qc

0 < 1 < 2 < 9

=> Số 0 nhỏ nhất

a) 4/5 . x = 4/7

⇒ x = 4/7 : 4/5 = 4/7 . 5/4 = 20/28 = 5/7

b) 3/4 : x = 1/2

⇒ x = 3/4 : 1/2 = 3/4 . 2/1 = 6/4 = 3/2