Question 1152110
y, Yolanda
j, Jeff
c, Clara


{{{system(y=j+7,j=3c,y+j+c=21)}}}



More than one way to go.


You could try sub for j.
{{{system(y=3c+7,y+3c+c=21)}}}


{{{3c+7+3c+c=21}}}
{{{7c+7=21}}}
{{{c+1=3}}}
{{{highlight(c=2)}}}