Step-by-step explanation:
an account transaction log is simply a sequence of basic additions and subtractions.
he made a mistake in line 4 : $180 - $188 = -$8 and not $8.
he missed that this was going below zero and needed a "-" sign.
from there on everything else is wrong too (although the individual calculations are correct) - the balances are off by $16 (2×8 from -8 to +8) :
+$20 gave the real balance of $12 and not $28.
-$5.95 gave the real balance of $6.05 and not $22.05.
