perl -d
  DB<1> $equation = '979x + 87y - 8723z = 274320'

  DB<2> $vars='xyz'

  DB<3> $operators=qr/[-+*\/%=]/

  DB<4> x $equation =~ /([^\s$vars]+|[$vars]|$operators)/g
0  979
1  'x'
2  '+'
3  87
4  'y'
5  '-'
6  8723
7  'z'
8  '='
9  274320