Answer:
General Journal Debit Credit
Amortization expenses $6,000,000
Patent $6,000,000
Calculation of annual amortization after the estimate change
Cost $21,600,000
Less: Amortization till date $9,600,000
($2,400,000*4 years)
Un-amortized Cost A $12,000,000
Remaining Life (6yrs-4yrs) 2 Years
New annual amortization $6,000,000
Old annual amortization = $21,600,000 / 9 years = $2,400,000
Amortization till date = $2,400,000 * 4 = $9,600,000