a) 21/20 : 4/5
= 21/16
b) x = 8/7+3/9
x = 31/21
a) 7/5 x 3/4 : 4/5 = 21/20 : 4/5
= 21/16
Tìm x:
b) x - 3/9 = 8/7
x = 8/7 + 3/9
X = 31/21
\(\dfrac{7}{5}\times\dfrac{3}{4}:\dfrac{4}{5}=\dfrac{7}{5}\times\dfrac{3}{4}\times\dfrac{5}{4}=\dfrac{7\times3\times5}{5\times4\times4}=\dfrac{7\times3}{4\times4}=\dfrac{21}{16}\)
b) \(x-\dfrac{3}{9}=\dfrac{8}{7}\)
\(x=\dfrac{8}{7}+\dfrac{3}{9}\)
\(x=\dfrac{72}{63}+\dfrac{21}{63}\)
\(x=\dfrac{93}{63}\)
\(x=\dfrac{31}{21}\)
