Question 1199417
h, home team fans
v, visiting team fans


{{{system(h=7+4v,h-v=12)}}}-----the description


{{{system(h-4v=7,h-v=12)}}}

E2-E1:
{{{3v=5}}}---------------Makes no sense.


Another Try:
{{{h-v=12}}}
substitute h,
{{{7+4v-v=12}}}
{{{3v=5}}}------------Makes no sense.