Bài 2
a) \(25:75=x:\dfrac{3}{5}\)
\(\Rightarrow\dfrac{25}{75}=x.\dfrac{5}{3}\)
\(\Rightarrow\dfrac{1}{3}=x.\dfrac{5}{3}\)
\(\Rightarrow x=\dfrac{1}{3}:\dfrac{5}{3}\)
\(\Rightarrow x=\dfrac{1}{5}\)
b) \(x:2,4=3:75\)
\(\Rightarrow x:\dfrac{12}{5}=\dfrac{1}{25}\)
\(\Rightarrow x=\dfrac{1}{25}.\dfrac{12}{5}\)
\(\Rightarrow x=\dfrac{12}{125}\)
Bài 1:
\(a,\dfrac{x}{3}=\dfrac{-9}{27}\\ =>\dfrac{x}{3}=\dfrac{-1}{3}\\ =>x=-1\\ b,\dfrac{0,16}{x}=\dfrac{0,32}{8}\\ =>x=\dfrac{0,16\cdot8}{0,32}\\ =>x=4\\ c,\dfrac{-25}{-2}=\dfrac{50}{x}\\ =>\dfrac{50}{x}=\dfrac{25}{2}\\ =>x=\dfrac{50\cdot2}{25}\\ =>x=4\\ d,\dfrac{7}{-49}=\dfrac{x}{-28}\\ =>\dfrac{x}{28}=\dfrac{1}{7}\\ =>x=\dfrac{28}{7}\\ =>x=4\)
Bài 3:
a: \(\dfrac{3x-2}{4}=\dfrac{5}{2}\)
=>\(3x-2=4\cdot\dfrac{5}{2}=10\)
=>3x=10+2=12
=>\(x=\dfrac{12}{3}=4\)
b: \(\dfrac{2x-1}{4}=\dfrac{28}{16}\)
=>\(2x-1=\dfrac{28}{16}\cdot4=\dfrac{7}{4}\cdot4=7\)
=>2x=8
=>x=4
c: \(\dfrac{9x+3}{9}=\dfrac{8}{3}\)
=>\(9x+3=9\cdot\dfrac{8}{3}=3\cdot8=24\)
=>9x=21
=>\(x=\dfrac{21}{9}=\dfrac{7}{3}\)
d: \(\dfrac{6x-12}{1,5}=\dfrac{7}{2,5}\)
=>\(6x-12=7\cdot\dfrac{1.5}{2.5}=7\cdot\dfrac{3}{5}=\dfrac{21}{5}=4,2\)
=>6x=4,2+12=16,2
=>\(x=\dfrac{16.2}{6}=2,7\)