42/25 . x/5 = 6/5
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\(a.\dfrac{12+x}{42}=\dfrac{35}{42}\Leftrightarrow12+x=35\Leftrightarrow x=23\)
\(b.\dfrac{25-x}{40}=\dfrac{3}{8}\Leftrightarrow\dfrac{25-x}{40}=\dfrac{15}{40}\Leftrightarrow25-x=15\Leftrightarrow x=10\)
\(c.\dfrac{13+x}{20}=\dfrac{3}{4}\Leftrightarrow\dfrac{13+x}{20}=\dfrac{15}{20}\Leftrightarrow13+x=15\Leftrightarrow x=2\)
\(d.\dfrac{23-x}{25}=\dfrac{20}{25}\Leftrightarrow23-x=20\Leftrightarrow x=3\)
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\(\frac{42}{25}\div\frac{x}{5}=\frac{6}{5}\)
\(\frac{x}{5}=\frac{42}{25}\div\frac{6}{5}\)
\(\frac{x}{5}=\frac{42}{25}\times\frac{5}{6}\)
\(\frac{x}{5}=\frac{7}{5}\)
\(x=7\)
\(\frac{42}{25}:\frac{x}{5}=\frac{6}{5}\)
\(\frac{x}{5}=\frac{42}{25}:\frac{6}{5}\)
\(\frac{x}{5}=\frac{42}{25}.\frac{5}{6}\)
\(\frac{x}{5}=\frac{7}{5}\)
\(\Rightarrow x=7\)
Vậy \(x=7\)
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\(a,12+\frac{x}{42}=\frac{5}{6}\)
\(\Rightarrow\frac{x}{42}=\frac{5}{6}-12\)
\(\Rightarrow\frac{x}{42}=\frac{-67}{6}\)
\(\Leftrightarrow6x=42\times(-67)\)
\(\Leftrightarrow6x=-2814\)
\(\Leftrightarrow x=-2814\div6=-469\)
Vậy x = -469
\(b,25-\frac{x}{40}=\frac{3}{8}\)
\(\frac{x}{40}=25-\frac{3}{8}\)
\(\frac{x}{40}=\frac{197}{8}\)
\(\Leftrightarrow8x=40\times197\)
\(\Leftrightarrow8x=7880\)
\(\Leftrightarrow x=7880\div8=985\)
Vậy x = 985
Chúc bạn học tốt
a, \(12+\frac{x}{42}=\frac{5}{6}\Leftrightarrow\frac{x}{42}=-\frac{67}{6}\Leftrightarrow\frac{x}{42}=\frac{-469}{42}\)
Khử mẫu đi ta đc : \(x=-469\)
b, \(25-\frac{x}{40}=\frac{3}{8}\Leftrightarrow\frac{x}{40}=\frac{197}{8}\Leftrightarrow\frac{x}{40}=\frac{985}{40}\)
Khử mẫu đi ta đc : \(x=985\)
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a: =23 giờ 63 phút
=24 giờ 3 phút
b: =606 giờ-105 giờ=501 giờ
c: =15 giờ 135 phút
=17 giờ 15 phút
d: =2550 giây:5
=510 giây
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( 5 + 10 + 15 + 20 + 25 + 30 + 35 ) x ( 42 - 6 x 7 )
= ( 5 + 10 + 15 + 20 + 25 + 30 + 35 ) x ( 42 - 42 )
= ( 5 + 10 + 15 + 20 + 25 + 30 + 35 ) x 0
= 0
42/25 * x/5 = 6/5
x/5 = 5/7
x= 25/7