x + 3/4 x 7/10 = 53/40
x + 21/40 = 53/40
x = 53/40 - 21/40
x = 32/40
x = 4/5
34/35 : x = 17/5
x = 34/35 : 17/5
x = 34/35 x 5/17
x = 2/7
x + 3/4 x 7/10 = 53/40
x + ( 3/4 x 7/10 ) = 53/40
x + 21/40 = 53/40 ( tới đây bn cứ lm như bth )
x = 53/40 - 21/40
x = 4/5
34/35 : x = 17/5
x = 34/35 : 17/5
x = 2/7
\(a,\) \(x+\dfrac{3}{4}\times\dfrac{7}{10}=\dfrac{53}{40}\)
\(x+\dfrac{21}{40}=\dfrac{53}{40}\)
\(x=\dfrac{53}{40}-\dfrac{21}{40}\)
\(x=\dfrac{4}{5}\)
\(b,\) \(\dfrac{34}{35}:x=\dfrac{17}{5}\)
\(x=\dfrac{34}{35}:\dfrac{17}{5}\)
\(x=\dfrac{2}{7}\)