Question 950508
R-Red
B-Black
U-Blue
{{{R+B+U=20}}}
{{{B=2+R}}}
{{{U=4+B=4+2+R=6+R}}}
Substitute,
{{{R+2+R+6+R=20}}}
{{{3R+8=20}}}
{{{3R=12}}}
{{{R=4}}}
So then,
{{{B=2+4}}}
{{{B=6}}}
and
{{{U=6+4}}}
{{{U=10}}}