Question

Determine x,y na proporçã x/y=3/4, sabendo-se que x+y= 84

Answer 1

$\frac{x}{y} = \frac{3}{4}$
$4x = 3y$  $x = 3y/4$

x + y = 84

$\frac{3y}{4} + y$ = 84

$\frac{3y}{4} + \frac{4y}{4} = 84$

$\frac{7y}{4} = 84$

$7y = 84*4$
$7y = 336$

$y = \frac{336}{7}$
$y = 48$

x + y = 84
x + 48 = 84
x = 84 - 48
x = 36

$\left \{ {{x=36} \atop {y=48}} \right.$