Question 176354
To go from
{{{(2x)/(5y)}}}
{{{(2/5)(x/y)}}}
to 
{{{(x/y)}}}
you need to use the multiplicative inverse of the coefficient in front of {{{(x/y)}}}.
The multiplicative inverse of (2/5) is (5/2) since
{{{(2/5)(5/2)=1}}}

So then you multiply both sides by (5/2), to get {{{(x/y)}}} by itself on the left hand side.
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If you multiply both sides by (2/5), you'd get,
{{{(2/5)(x/y)=3/4}}}

{{{(2/5)(2/5)(x/y)=(2/5)(3/4)}}}
{{{(4/25)(x/y)=3/10}}}