\(\dfrac{10}{18}\) < \(\dfrac{15}{x}\) < \(\dfrac{10}{17}\)
\(\dfrac{10\times3}{18\times3}\) < \(\dfrac{15\times2}{x\times2}\) < \(\dfrac{10\times3}{17\times3}\)
\(\dfrac{30}{54}\) < \(\dfrac{30}{x\times2}\) < \(\dfrac{30}{51}\)
54 > \(x\times\) 2 > 51
Vì 54 > 53 > 52 > 51
\(x\) \(\times\) 2 = 52
\(x\) = 52: 2
\(x\) = 26
tooi ko biết ..................................................................................................................................................................................................................................................................................................................................................................................................................
21 – 1350 – 1350x 
