# Pastebin n8NRGXvY
% perl6 -I. -MConstraint -e '
my $*PRINT-ISOLATED = True;
my &f2c = formula -> :$c, :$f { 9 * $c == 5 * ($f - 32) }

say f2c(:0f);
say f2c(:0c)
'
c == ( ( 5 * ( 0 - 32 ) ) / 9 )
{c => -17.777778, f => 0}
f == ( ( ( 9 * 0 ) / 5 ) + 32 )
{c => 0, f => 32}