Question

Urgentes me ajudem por favor !!!

aplicando as propriedades resolva as proporções
a) x/y=1/2 sabendo que x+y=90

b)7/3=x/y, sabendo que x+y= 80

c) x/y=5/4,sabendo que x-y=12

Answer 1

a) $\dfrac{x}{y}=\dfrac{1}{2}$

$y=2x$

$x+y=90$

$x+2x=90$

$3x=90$

$x=30$

$y=60$

b) $\dfrac{x}{y}=\dfrac{7}{3}$

$3x=7y$

$x=\dfrac{7y}{3}$

$x+y=80$

$\dfrac{7y}{3}+y=80$

$7y+3y=240$

$10y=240$

$y=24$

$x=\dfrac{7\cdot24}{3}=56$

c) $\dfrac{x}{y}=\dfrac{5}{4}$

$4x=5y$

$x=\dfrac{5y}{4}$

$x-y=12$

$\dfrac{5y}{4}-y=12$

$5y-4y=48$

$y=48$

$x=\dfrac{5\cdot48}{4}=60$