Question 877509
{{{B/G=3/5}}}
{{{B=(3/5)G}}}
.
.

{{{B+G=800}}}

Substitute,
{{{(3/5)G+G=800}}}
{{{(8/5)G=800}}}
{{{G=500}}}
{{{B=(3/5)500}}}
{{{B=300}}}