Compound Interest Problem: When Will Mr. Weasley's Liabilities Be Cancelled?

[pixie]

Can anyone help me with this problem? I'm stuck

When will a payment of 300,000 galleons cancel Mr. Weasley’s liabilities to Gringott’s Bank of 100,000 galleons due after 2 years and 150,000 galleons due after 5 years if money is worth at an effective rate of 12%?

 

[Wilmer]

When will a payment of 300,000 galleons cancel Mr. Weasley’s liabilities to Gringott’s Bank of 100,000 galleons due after 2 years and 150,000 galleons due after 5 years if money is worth at an effective rate of 12%?

HINT:
u = PV of the 100,000
v = PV of the 150,000
w = PV of the 300,000
w = u + v

You'll need to use logs:
remember that if a^p = x, then p = log(x) / log(a)