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\(\frac{2}{7}\)A = \(\frac{3}{10}\)B x \(\frac{4}{9}\)= \(\frac{2}{15}\)B => \(\frac{A}{B}\)= \(\frac{2}{15}\)\(=\frac{7}{15}\)
\(\frac{2}{7}\)
Câu hỏi của nguyễn ngọc khánh vân - Toán lớp 7 - Học toán với OnlineMath
Em tham khảo nhé!
ta có 2/7 của A = 4/9 . 3/10 .B
=> 2/7 . A = 2/15 . B
=> A = 2/15 . B : 2/7
=> A = 7/15 . B
vậy A= 7/15 của B
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Theo bài ra ta có:
\(\dfrac{2}{7}A=\dfrac{9}{4}.\dfrac{3}{10}B\\ \Rightarrow\dfrac{2}{7}A=\dfrac{27}{40}B\\ \Rightarrow\dfrac{A}{B}=\dfrac{\dfrac{27}{40}}{\dfrac{2}{7}}=\dfrac{189}{80}\)
\(\dfrac{2}{7}\)A=\(\dfrac{3}{10}\).\(\dfrac{4}{9}\)
⇒\(\dfrac{2}{7}\)A=\(\dfrac{2}{15}\)B
⇒\(\dfrac{A}{\dfrac{2}{15}}=\dfrac{B}{\dfrac{2}{7}}\)
\(\dfrac{A}{B}=\dfrac{2}{\dfrac{15}{\dfrac{2}{7}}}\)
⇒\(\dfrac{A}{B}=\dfrac{7}{15}\)