9/5 =18/10=1,8
 2/25 =8/100=0,08
23/8 =2874/1000=2,874
76/4 =1900/100=19
42/25 =168/100=1,68

9/5 = 18/10 = 1,8

2/25 = 8/100 = 0,08

23/8 = 2875/1000 = 2,875

76/4 = 1900/100 = 19,00 = 19

42/25 = 168/100 = 1,68

9/5 =\(\dfrac{90}{50}=1,8\)

2/25 =\(\dfrac{20}{250}=0,08\)

23/8 =\(\dfrac{23}{8}=2,875\)

76/4 =\(\dfrac{76}{40}=\dfrac{19}{10}\)

42/25 =\(\dfrac{420}{250}=1,68\)

\(A=15^{28}=(15^2)^{14}=225^{14}\)

\(B=6^{42}=(6^3)^{14}=216^{14}\)

Mà \(225>216\)nên \(15^{28}>6^{42}\)hoặc \(A>B\)

Mình chỉ làm tạm thôi nha bạn

f: =703-2-289=703-291=412

\(703-140:\left(42+28\right)-17^{15}:17^{13}\)
\(=730-140:70-17^2\)
\(=730-2-289\)
\(=439\)

\(\frac{11}{13}-\left(\frac{5}{42}-x\right)=-\left(\frac{15}{28}-\frac{11}{13}\right)\)

\(=\frac{11}{13}-\left(\frac{5}{42}-x\right)=\frac{113}{364}\)

\(\Rightarrow\frac{5}{42}-x=\frac{11}{13}-\frac{113}{364}\)

\(\Rightarrow x=\frac{5}{42}-\frac{15}{28}\)

\(\Rightarrow x=\frac{-5}{12}\)

\(\frac{11}{13}-\left(\frac{5}{42}-x\right)=-\left(\frac{15}{28}-\frac{11}{13}\right)\)

<=> \(\frac{11}{13}-\frac{5}{42}+x=-\left(-\frac{113}{364}\right)\)

<=> \(\frac{397}{546}+x=\frac{113}{364}\)

<=> \(x=\frac{-5}{12}\)

học tốt

\(\frac{1}{13}-\left(\frac{5}{42}-x\right)=-\left(-\frac{113}{364}\right)\)

=>\(\frac{1}{13}-\frac{5}{42}+x=\frac{113}{364}\)

=>\(-\frac{23}{546}+x=\frac{113}{364}\)

=>\(x=\frac{113}{364}-\left(-\frac{23}{546}\right)\)

=>\(x=\frac{113}{364}+\frac{23}{546}\)

=>\(x=\frac{55}{156}\)