In any transaction,
the total money paid = total money collected
the 3 guys paid N90 each (no doubt about that)
there4, total money paid = (N90 x 3) = N270
And total money collected = N250 + N20 = N270
Thus total money paid=total money collected QED
The fact is that the total money 'transacted' was actually N270 as opposed to N3000 believed to have been transacted by laz4rich and there4 there was never any missing N10 or amount for that matter.