a,

= (20 x 5)x 3 246

= 100 x 3 246

= 324 600

b,

= 346 x (53 + 47)

= 346 x 100

= 34 600

21​ tấn < 400 yến

\(\frac{2}{5}\) \(m^{2}\) > 3 000 \(\left(cm ⁡\right)^{2}\)

\(\frac{7}{12}\) giờ < 40 phút

\(\frac{1}{4}\) km = 250 m

 \(\frac{7}{24}\) + \(\frac{13}{6}\) = \(\frac{7}{24}\) + \(\frac{52}{24}\) = \(\frac{59}{24}\)

b) \(\frac{12}{49}\) - \(\frac{1}{7}\) = \(\frac{12}{49}\) - \(\frac{7}{49}\) = \(\frac{5}{49}\)

c) \(\frac{5}{8}\) x \(\frac{24}{25}\) = \(\frac{120}{200}\) = \(\frac{3}{5}\)

d) \(\frac{38}{21}\) : \(\frac{19}{3}\) = \(\frac{38}{21}\) x \(\frac{3}{19}\) = \(\frac{114}{399}\) = \(\frac{38}{133}\)

a, 34 287 557 130:42=13265

x

65

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205 715