\(\left(x+5\right)\cdot19:13=5.7\)

\(\left(x+5\right)\cdot19=5.7\cdot13\)

\(\left(x+5\right)\cdot19=74.1\)

\(x+5=74.1:19\)

\(x+5=3.9\)

\(x=3.9-5\)

\(x=-1.1\)

\(\left(x+5\right)\times19\div13=5,7\)

\(\Rightarrow x\times19\div13=5,7\)

\(\Rightarrow x=5,7\div19\times13\)

\(\Rightarrow x=3,9\)

\(\Rightarrow x=3,9-5\)

\(\Rightarrow x=-1,1\)

5,7 × (179 - 130) + (3,4 + 2,3) × (32 + 19)

= 5,7 × 49 + 5,7 × 51

= 5,7 × (49 + 51)

= 5,7 × 100

= 5700

5,7 × (179 - 130) + (3,4 + 2,3) × (32 + 19)

= 5,7 × 49 + 5,7 × 51

= 5,7 × (49 + 51)

= 5,7 × 100

= 5700

\(A=\frac{\left(1374\times5,7+687\times8,6\right)}{\left(26\times13+74\times14\right)}\)

\(A=\frac{\left(7831,8+5908,2\right)}{\left(338+1036\right)}\)

\(A=\frac{13740}{1374}\)

\(\Rightarrow A=10\)

a: \(=\dfrac{17}{19}\cdot\dfrac{19}{17}\cdot\dfrac{4}{5}=\dfrac{4}{5}\)

b: \(=\dfrac{14}{7}\cdot\dfrac{7}{6}=2\cdot\dfrac{7}{6}=\dfrac{14}{6}=\dfrac{7}{3}\)

c: =13/14(4/5+1/5)=13/14

\(\dfrac{17}{19}\times\dfrac{12}{15}\times\dfrac{19}{17}=\dfrac{12}{15}\)

\(\left(\dfrac{5}{7}+\dfrac{9}{7}\right)\times\dfrac{21}{18}=2\times\dfrac{7}{6}=\dfrac{7}{3}\)

\(\dfrac{4}{5}\times\dfrac{13}{14}+\dfrac{13}{14}\times\dfrac{1}{5}=\dfrac{13}{14}\)

\(\dfrac{17}{19}\times\dfrac{12}{15}\times\dfrac{19}{17}.\\ =\dfrac{17}{19}\times\dfrac{19}{17}\times\dfrac{12}{15}.\\ =1\times\dfrac{12}{15}=\dfrac{12}{15}.\\ \left(\dfrac{5}{7}+\dfrac{9}{7}\right)\times\dfrac{21}{18}.\\ =2\times\dfrac{7}{6}=\dfrac{7}{3}.\\ \dfrac{4}{5}\times\dfrac{13}{14}+\dfrac{13}{14}\times\dfrac{1}{5}.\\ =\left(\dfrac{4}{5}+\dfrac{1}{5}\right)\times\dfrac{13}{14}.\\ =1\times\dfrac{13}{14}.\\ =\dfrac{13}{14}.\)

Bài 1 :

\(a)x=\frac{7}{25}+\left(-\frac{1}{5}\right)\)

    \(x=\frac{2}{25}\)

\(b)x=\frac{5}{11}+\left(\frac{4}{-9}\right)\)

    \(x=\frac{1}{99}\)

Mấy câu kia dễ tự làm :>