Answer:
 assets = liabilities + equity
a) NA - $6,400 AP
 + $6,400 NP
 net effect $0
b) NA + $128 interest - $128 retained 
 payable earnings
c) -$6,528 cash -$6,400 NP NA
 -$128 interest p. 
 revenue - expenses = income
a) NA NA NA
b) $0 $128 -$128
c) NA NA NA