Using a hypothetical example where an account used a D40 box for 24 days with normal
free time at 6 days, and where Slab 1 demurrage rate is $30/day from Day 7 to Day 14
and Slab 2 rate is $50/day from Day 15 onwards, the demurrage due will be ($30 x 7) +
($50 x 11) = $760.