Question 878973
x/y=3/4 and x+y=84 and xy=432.

x=3y/4.

{{{3y/4+y=84}}} and {{{(3y/x)y=432}}};
{{{3y/4+4y/4=84}}} and {{{3y^2=432x}}};
{{{7y/4=84}}}
{{{7y=84*4}}}
{{{y=12*4}}}
{{{highlight(y=48)}}} and {{{3*48^2=432x}}};
{{{x=(1/432)3*48^2}}}
{{{highlight(x=16)}}}