Question 891107
{{{X/Y=3/5}}}
{{{5X=3Y}}}
{{{X=(3/5)Y}}}
.
.
.
{{{Y^2-X^2=400}}}
{{{(Y-X)(Y+X)=400}}}
{{{(Y-(3/5)Y)(Y+(3/5)Y)=400}}}
{{{(2/5)Y(8/5)Y=400}}}
{{{(16/25)Y^2=400}}}
{{{(4/5)Y=20}}}
{{{Y=25}}}
Then,
{{{X=(3/5)25}}}
{{{X=15}}}