if , (4x + 3y) : (3x + 4y) = 24 : 25 , find the value of x : y .

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Sagot :

We have ( 4x + 3y ) : ( 3x + 4y ) = 24 : 25

[tex]\\ \sf\longmapsto \: \frac{4x + 3y}{3x + 4y} = \frac{24}{25} [/tex]

[tex]\\ \sf\longmapsto \: 25(4x + 3y) = 24(3x + 4y)[/tex]

[tex]\\ \sf\longmapsto \: 100x + 75y = 72x + 96y[/tex]

[tex]\\ \sf\longmapsto \: 100x - 72x = 96y - 75y[/tex]

[tex]\\ \sf\longmapsto \: 28x = 21y[/tex]

[tex]\\ \sf\longmapsto \: \frac{x}{y} = \frac{21}{28} = \frac{3}{4} [/tex]

Hence ,

  • x : y = 3 : 4

[tex]\\ \sf\longmapsto \dfrac{4x+3y}{3x+4y}=\dfrac{24}{25}[/tex]

  • Use cross multiplication

[tex]\\ \sf\longmapsto 24(3x+4y)=25(4x+3y)[/tex]

[tex]\\ \sf\longmapsto 72x+96y=100x+75y[/tex]

[tex]\\ \sf\longmapsto 96y-75y=100x-72x[/tex]

[tex]\\ \sf\longmapsto 21y=28x[/tex]

[tex]\\ \sf\longmapsto \dfrac{x}{y}=\dfrac{21}{28}[/tex]

  • Cut 7

[tex]\\ \sf\longmapsto \dfrac{x}{y}=\dfrac{3}{4}[/tex]

[tex]\\ \sf\longmapsto x:y=3:4[/tex]